diff --git a/test/mjsunit/compiler/assignment.js b/test/mjsunit/compiler/assignment.js
index ee2d323..6aded4e 100644
--- a/test/mjsunit/compiler/assignment.js
+++ b/test/mjsunit/compiler/assignment.js
@@ -262,3 +262,15 @@
 }
 
 bar_loop();
+
+
+// Test for assignment using a keyed store ic:
+function store_i_in_element_i_of_object_i() {
+  var i = new Object();
+  i[i] = i;
+}
+
+// Run three times to exercise caches.
+store_i_in_element_i_of_object_i();
+store_i_in_element_i_of_object_i();
+store_i_in_element_i_of_object_i();
diff --git a/test/mjsunit/object-define-property.js b/test/mjsunit/object-define-property.js
index 43b1c7f..46bfb34 100644
--- a/test/mjsunit/object-define-property.js
+++ b/test/mjsunit/object-define-property.js
@@ -53,36 +53,46 @@
   assertTrue(/called on non-object/.test(e));
 }
 
-// Object
+// Object.
 var obj1 = {};
 
-// Values
+// Values.
 var val1 = 0;
 var val2 = 0;
 var val3 = 0;
 
-// Descriptors
+function setter1() {val1++; }
+function getter1() {return val1; }
+
+function setter2() {val2++; }
+function getter2() {return val2; }
+
+function setter3() {val3++; }
+function getter3() {return val3; }
+
+
+// Descriptors.
 var emptyDesc = {};
 
 var accessorConfigurable = { 
-    set: function() { val1++; },
-    get: function() { return val1; },
+    set: setter1,
+    get: getter1,
     configurable: true
 };
 
 var accessorNoConfigurable = {
-    set: function() { val2++; },
-    get: function() { return val2; },
+    set: setter2,
+    get: getter2,
     configurable: false 
 };
 
 var accessorOnlySet = {
-  set: function() { val3++; },
+  set: setter3,
   configurable: true
 };
 
 var accessorOnlyGet = {
-  get: function() { return val3; },
+  get: getter3,
   configurable: true
 };
 
@@ -200,7 +210,7 @@
 assertEquals(4, val2);
 assertEquals(4, obj1.bar);
 
-// Define an accessor that has only a setter
+// Define an accessor that has only a setter.
 Object.defineProperty(obj1, "setOnly", accessorOnlySet);
 desc = Object.getOwnPropertyDescriptor(obj1, "setOnly");
 assertTrue(desc.configurable);
@@ -212,7 +222,7 @@
 assertEquals(1, obj1.setOnly = 1);
 assertEquals(1, val3);
 
-// Add a getter - should not touch the setter
+// Add a getter - should not touch the setter.
 Object.defineProperty(obj1, "setOnly", accessorOnlyGet);
 desc = Object.getOwnPropertyDescriptor(obj1, "setOnly");
 assertTrue(desc.configurable);
@@ -256,7 +266,7 @@
 assertEquals(obj1.foobar, 1000);
 
 
-// Redefine to writable descriptor - now writing to foobar should be allowed
+// Redefine to writable descriptor - now writing to foobar should be allowed.
 Object.defineProperty(obj1, "foobar", dataWritable);
 desc = Object.getOwnPropertyDescriptor(obj1, "foobar");
 assertEquals(obj1.foobar, 3000);
@@ -279,7 +289,7 @@
 assertEquals(obj1.foobar, 2000);
 assertEquals(desc.value, 2000);
 assertFalse(desc.configurable);
-assertFalse(desc.writable);
+assertTrue(desc.writable);
 assertFalse(desc.enumerable);
 assertEquals(desc.get, undefined);
 assertEquals(desc.set, undefined);
@@ -307,7 +317,7 @@
 assertEquals(obj1.foobar, 2000);
 assertEquals(desc.value, 2000);
 assertFalse(desc.configurable);
-assertFalse(desc.writable);
+assertTrue(desc.writable);
 assertFalse(desc.enumerable);
 assertEquals(desc.get, undefined);
 assertEquals(desc.set, undefined);
@@ -375,7 +385,7 @@
 
 
 // Redefinition of an accessor defined using __defineGetter__ and 
-// __defineSetter__
+// __defineSetter__.
 function get(){return this.x}
 function set(x){this.x=x};
 
@@ -442,7 +452,7 @@
 assertEquals(5, val1);
 assertEquals(5, obj4.bar);
 
-// Make sure an error is thrown when trying to access to redefined function
+// Make sure an error is thrown when trying to access to redefined function.
 try {
   obj4.bar();
   assertTrue(false);
@@ -453,7 +463,7 @@
 
 // Test runtime calls to DefineOrRedefineDataProperty and
 // DefineOrRedefineAccessorProperty - make sure we don't 
-// crash
+// crash.
 try {
   %DefineOrRedefineAccessorProperty(0, 0, 0, 0, 0);
 } catch (e) {
@@ -497,3 +507,210 @@
 } catch (e) {
   assertTrue(/illegal access/.test(e));
 }
+
+// Test that all possible differences in step 6 in DefineOwnProperty are
+// exercised, i.e., any difference in the given property descriptor and the
+// existing properties should not return true, but throw an error if the
+// existing configurable property is false. 
+
+var obj5 = {};
+// Enumerable will default to false.
+Object.defineProperty(obj5, 'foo', accessorNoConfigurable);
+desc = Object.getOwnPropertyDescriptor(obj5, 'foo');
+// First, test that we are actually allowed to set the accessor if all
+// values are of the descriptor are the same as the existing one.
+Object.defineProperty(obj5, 'foo', accessorNoConfigurable);
+
+// Different setter.
+var descDifferent = {
+  configurable:false,
+  enumerable:false,
+  set: setter1,
+  get: getter2
+};
+
+try {
+  Object.defineProperty(obj5, 'foo', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// Different getter.
+descDifferent = {
+  configurable:false,
+  enumerable:false,
+  set: setter2,
+  get: getter1
+};
+
+try {
+  Object.defineProperty(obj5, 'foo', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// Different enumerable.
+descDifferent = {
+  configurable:false,
+  enumerable:true,
+  set: setter2,
+  get: getter2
+};
+
+try {
+  Object.defineProperty(obj5, 'foo', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// Different configurable.
+descDifferent = {
+  configurable:false,
+  enumerable:true,
+  set: setter2,
+  get: getter2
+};
+
+try {
+  Object.defineProperty(obj5, 'foo', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// No difference.
+descDifferent = {
+  configurable:false,
+  enumerable:false,
+  set: setter2,
+  get: getter2
+};
+// Make sure we can still redefine if all properties are the same.
+Object.defineProperty(obj5, 'foo', descDifferent);
+
+// Make sure that obj5 still holds the original values.
+desc = Object.getOwnPropertyDescriptor(obj5, 'foo');
+assertEquals(desc.get, getter2);
+assertEquals(desc.set, setter2);
+assertFalse(desc.enumerable);
+assertFalse(desc.configurable);
+
+
+// Also exercise step 6 on data property, writable and enumerable
+// defaults to false.
+Object.defineProperty(obj5, 'bar', dataNoConfigurable);
+
+// Test that redefinition with the same property descriptor is possible
+Object.defineProperty(obj5, 'bar', dataNoConfigurable);
+
+// Different value.
+descDifferent = {
+  configurable:false,
+  enumerable:false,
+  writable: false,
+  value: 1999
+};
+
+try {
+  Object.defineProperty(obj5, 'bar', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// Different writable.
+descDifferent = {
+  configurable:false,
+  enumerable:false,
+  writable: true,
+  value: 2000
+};
+
+try {
+  Object.defineProperty(obj5, 'bar', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+
+// Different enumerable.
+descDifferent = {
+  configurable:false,
+  enumerable:true ,
+  writable:false,
+  value: 2000
+};
+
+try {
+  Object.defineProperty(obj5, 'bar', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+
+// Different configurable.
+descDifferent = {
+  configurable:true,
+  enumerable:false,
+  writable:false,
+  value: 2000
+};
+
+try {
+  Object.defineProperty(obj5, 'bar', descDifferent);
+  assertTrue(false);
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+// No difference.
+descDifferent = {
+  configurable:false,
+  enumerable:false,
+  writable:false,
+  value:2000
+};
+// Make sure we can still redefine if all properties are the same.
+Object.defineProperty(obj5, 'bar', descDifferent);
+
+// Make sure that obj5 still holds the original values.
+desc = Object.getOwnPropertyDescriptor(obj5, 'bar');
+assertEquals(desc.value, 2000);
+assertFalse(desc.writable);
+assertFalse(desc.enumerable);
+assertFalse(desc.configurable);
+
+
+// Make sure that we can't overwrite +0 with -0 and vice versa.
+var descMinusZero = {value: -0, configurable: false};
+var descPlusZero = {value: +0, configurable: false};
+
+Object.defineProperty(obj5, 'minuszero', descMinusZero);
+
+// Make sure we can redefine with -0.
+Object.defineProperty(obj5, 'minuszero', descMinusZero);
+
+try {
+  Object.defineProperty(obj5, 'minuszero', descPlusZero);
+  assertUnreachable();
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
+
+
+Object.defineProperty(obj5, 'pluszero', descPlusZero);
+
+// Make sure we can redefine with +0.
+Object.defineProperty(obj5, 'pluszero', descPlusZero);
+
+try {
+  Object.defineProperty(obj5, 'pluszero', descMinusZero);
+  assertUnreachable();
+} catch (e) {
+  assertTrue(/Cannot redefine property/.test(e));
+}
diff --git a/test/mjsunit/regress/regress-712.js b/test/mjsunit/regress/regress-712.js
new file mode 100644
index 0000000..b26b94a
--- /dev/null
+++ b/test/mjsunit/regress/regress-712.js
@@ -0,0 +1,38 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This regression test is used to ensure that Object.defineProperty
+// can't be called with an empty property descriptor on a non-configurable
+// existing property and override the existing property.
+// See: http://code.google.com/p/v8/issues/detail?id=712
+
+var obj = {};
+Object.defineProperty(obj, "x", { get: function() { return "42"; },
+                                  configurable: false });
+assertEquals(obj.x, "42");
+Object.defineProperty(obj, 'x', {});
+assertEquals(obj.x, "42");
diff --git a/test/mjsunit/regress/regress-720.js b/test/mjsunit/regress/regress-720.js
new file mode 100644
index 0000000..97e1284
--- /dev/null
+++ b/test/mjsunit/regress/regress-720.js
@@ -0,0 +1,36 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This regression test is used to ensure that Object.defineProperty
+// keeps the existing value of the writable flag if none is given
+// in the provided descriptor. 
+// See: http://code.google.com/p/v8/issues/detail?id=720
+
+var o = {x: 10};
+Object.defineProperty(o, "x", {value: 5});
+var desc = Object.getOwnPropertyDescriptor(o, "x");
+assertTrue(desc["writable"]);
diff --git a/test/mjsunit/samevalue.js b/test/mjsunit/samevalue.js
new file mode 100644
index 0000000..6cb35e6
--- /dev/null
+++ b/test/mjsunit/samevalue.js
@@ -0,0 +1,102 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Flags: --expose-natives_as natives
+// Test the SameValue internal method.
+
+var obj1 = {x: 10, y: 11, z: "test"};
+var obj2 = {x: 10, y: 11, z: "test"};
+
+assertTrue(natives.SameValue(0, 0));
+assertTrue(natives.SameValue(+0, +0));
+assertTrue(natives.SameValue(-0, -0));
+assertTrue(natives.SameValue(1, 1));
+assertTrue(natives.SameValue(2, 2));
+assertTrue(natives.SameValue(-1, -1));
+assertTrue(natives.SameValue(0.5, 0.5));
+assertTrue(natives.SameValue(true, true));
+assertTrue(natives.SameValue(false, false));
+assertTrue(natives.SameValue(NaN, NaN));
+assertTrue(natives.SameValue(null, null));
+assertTrue(natives.SameValue("foo", "foo"));
+assertTrue(natives.SameValue(obj1, obj1));
+// Undefined values.
+assertTrue(natives.SameValue());
+assertTrue(natives.SameValue(undefined, undefined));
+
+assertFalse(natives.SameValue(0,1));
+assertFalse(natives.SameValue("foo", "bar"));
+assertFalse(natives.SameValue(obj1, obj2));
+assertFalse(natives.SameValue(true, false));
+
+assertFalse(natives.SameValue(obj1, true));
+assertFalse(natives.SameValue(obj1, "foo"));
+assertFalse(natives.SameValue(obj1, 1));
+assertFalse(natives.SameValue(obj1, undefined));
+assertFalse(natives.SameValue(obj1, NaN));
+
+assertFalse(natives.SameValue(undefined, true));
+assertFalse(natives.SameValue(undefined, "foo"));
+assertFalse(natives.SameValue(undefined, 1));
+assertFalse(natives.SameValue(undefined, obj1));
+assertFalse(natives.SameValue(undefined, NaN));
+
+assertFalse(natives.SameValue(NaN, true));
+assertFalse(natives.SameValue(NaN, "foo"));
+assertFalse(natives.SameValue(NaN, 1));
+assertFalse(natives.SameValue(NaN, obj1));
+assertFalse(natives.SameValue(NaN, undefined));
+
+assertFalse(natives.SameValue("foo", true));
+assertFalse(natives.SameValue("foo", 1));
+assertFalse(natives.SameValue("foo", obj1));
+assertFalse(natives.SameValue("foo", undefined));
+assertFalse(natives.SameValue("foo", NaN));
+
+assertFalse(natives.SameValue(true, 1));
+assertFalse(natives.SameValue(true, obj1));
+assertFalse(natives.SameValue(true, undefined));
+assertFalse(natives.SameValue(true, NaN));
+assertFalse(natives.SameValue(true, "foo"));
+
+assertFalse(natives.SameValue(1, true));
+assertFalse(natives.SameValue(1, obj1));
+assertFalse(natives.SameValue(1, undefined));
+assertFalse(natives.SameValue(1, NaN));
+assertFalse(natives.SameValue(1, "foo"));
+
+// Special string cases.
+assertFalse(natives.SameValue("1", 1));
+assertFalse(natives.SameValue("true", true));
+assertFalse(natives.SameValue("false", false));
+assertFalse(natives.SameValue("undefined", undefined));
+assertFalse(natives.SameValue("NaN", NaN));
+
+// -0 and +0 are should be different
+assertFalse(natives.SameValue(+0, -0));
+assertFalse(natives.SameValue(-0, +0));