Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/factory.cc b/src/factory.cc
index 2bc878c..96c757a 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -334,6 +334,11 @@
 }
 
 
+Handle<Map> Factory::GetPixelArrayElementsMap(Handle<Map> src) {
+  CALL_HEAP_FUNCTION(src->GetPixelArrayElementsMap(), Map);
+}
+
+
 Handle<FixedArray> Factory::CopyFixedArray(Handle<FixedArray> array) {
   CALL_HEAP_FUNCTION(array->Copy(), FixedArray);
 }
@@ -580,7 +585,9 @@
   // Set function.prototype and give the prototype a constructor
   // property that refers to the function.
   SetPrototypeProperty(function, prototype);
-  SetProperty(prototype, Factory::constructor_symbol(), function, DONT_ENUM);
+  // Currently safe because it is only invoked from Genesis.
+  SetLocalPropertyNoThrow(
+      prototype, Factory::constructor_symbol(), function, DONT_ENUM);
   return function;
 }
 
@@ -755,6 +762,24 @@
 }
 
 
+Handle<JSMessageObject> Factory::NewJSMessageObject(
+    Handle<String> type,
+    Handle<JSArray> arguments,
+    int start_position,
+    int end_position,
+    Handle<Object> script,
+    Handle<Object> stack_trace,
+    Handle<Object> stack_frames) {
+  CALL_HEAP_FUNCTION(Heap::AllocateJSMessageObject(*type,
+                                                   *arguments,
+                                                   start_position,
+                                                   end_position,
+                                                   *script,
+                                                   *stack_trace,
+                                                   *stack_frames),
+                     JSMessageObject);
+}
+
 Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(Handle<String> name) {
   CALL_HEAP_FUNCTION(Heap::AllocateSharedFunctionInfo(*name),
                      SharedFunctionInfo);