Update V8 to r6101 as required by WebKit r74534

Change-Id: I7f84af8dd732f11898fd644b2c2b1538914cb78d
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 5ea480f..1df9b47 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -74,12 +74,6 @@
 }
 
 
-void MacroAssembler::StackLimitCheck(Label* on_stack_overflow) {
-  CompareRoot(rsp, Heap::kStackLimitRootIndex);
-  j(below, on_stack_overflow);
-}
-
-
 void MacroAssembler::RecordWriteHelper(Register object,
                                        Register addr,
                                        Register scratch) {
@@ -1504,17 +1498,6 @@
 }
 
 
-void MacroAssembler::AbortIfNotString(Register object) {
-  testb(object, Immediate(kSmiTagMask));
-  Assert(not_equal, "Operand is not a string");
-  push(object);
-  movq(object, FieldOperand(object, HeapObject::kMapOffset));
-  CmpInstanceType(object, FIRST_NONSTRING_TYPE);
-  pop(object);
-  Assert(below, "Operand is not a string");
-}
-
-
 void MacroAssembler::AbortIfNotRootValue(Register src,
                                          Heap::RootListIndex root_value_index,
                                          const char* message) {
@@ -2267,6 +2250,31 @@
 }
 
 
+void MacroAssembler::LoadGlobalFunction(int index, Register function) {
+  // Load the global or builtins object from the current context.
+  movq(function, Operand(rsi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  // Load the global context from the global or builtins object.
+  movq(function, FieldOperand(function, GlobalObject::kGlobalContextOffset));
+  // Load the function from the global context.
+  movq(function, Operand(function, Context::SlotOffset(index)));
+}
+
+
+void MacroAssembler::LoadGlobalFunctionInitialMap(Register function,
+                                                  Register map) {
+  // Load the initial map.  The global functions all have initial maps.
+  movq(map, FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
+  if (FLAG_debug_code) {
+    Label ok, fail;
+    CheckMap(map, Factory::meta_map(), &fail, false);
+    jmp(&ok);
+    bind(&fail);
+    Abort("Global functions must have initial map");
+    bind(&ok);
+  }
+}
+
+
 int MacroAssembler::ArgumentStackSlotsForCFunctionCall(int num_arguments) {
   // On Windows 64 stack slots are reserved by the caller for all arguments
   // including the ones passed in registers, and space is always allocated for