Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/x64/code-stubs-x64.h b/src/x64/code-stubs-x64.h
index 9feced2..8051d4b 100644
--- a/src/x64/code-stubs-x64.h
+++ b/src/x64/code-stubs-x64.h
@@ -270,6 +270,11 @@
   void GenerateSmiCode(MacroAssembler* masm,
                        Label* slow,
                        SmiCodeGenerateHeapNumberResults heapnumber_results);
+  void GenerateFloatingPointCode(MacroAssembler* masm,
+                                 Label* allocation_failure,
+                                 Label* non_numeric_failure);
+  void GenerateStringAddCode(MacroAssembler* masm);
+  void GenerateCallRuntimeCode(MacroAssembler* masm);
   void GenerateLoadArguments(MacroAssembler* masm);
   void GenerateReturn(MacroAssembler* masm);
   void GenerateUninitializedStub(MacroAssembler* masm);
@@ -447,6 +452,25 @@
 };
 
 
+// Generate code the to load an element from a pixel array. The receiver is
+// assumed to not be a smi and to have elements, the caller must guarantee this
+// precondition. If the receiver does not have elements that are pixel arrays,
+// the generated code jumps to not_pixel_array. If key is not a smi, then the
+// generated code branches to key_not_smi. Callers can specify NULL for
+// key_not_smi to signal that a smi check has already been performed on key so
+// that the smi check is not generated . If key is not a valid index within the
+// bounds of the pixel array, the generated code jumps to out_of_range.
+void GenerateFastPixelArrayLoad(MacroAssembler* masm,
+                                Register receiver,
+                                Register key,
+                                Register elements,
+                                Register untagged_key,
+                                Register result,
+                                Label* not_pixel_array,
+                                Label* key_not_smi,
+                                Label* out_of_range);
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_X64_CODE_STUBS_X64_H_