Add EmitSlotAssignment to x64 platform.

src/x64/codegen-x64.h

 // 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
@@ skipping 436 matching lines @@
   void EmitDynamicLoadFromSlotFastCase(Slot* slot,
                                        TypeofState typeof_state,
                                        Result* result,
                                        JumpTarget* slow,
                                        JumpTarget* done);
 
   // Store the value on top of the expression stack into a slot, leaving the
   // value in place.
   void StoreToSlot(Slot* slot, InitState init_state);
 
+  // Support for compiling assignment expressions.
+  void EmitSlotAssignment(Assignment* node);
+
   // Receiver is passed on the frame and not consumed.
   Result EmitNamedLoad(Handle<String> name, bool is_contextual);
 
   // Load a property of an object, returning it in a Result.
   // The object and the property name are passed on the stack, and
   // not changed.
   Result EmitKeyedLoad();
 
   // Special code for typeof expressions: Unfortunately, we must
   // be careful when loading the expression in 'typeof'
@@ skipping 595 matching lines @@
     return ObjectBits::encode(object_.code()) |
            AddressBits::encode(addr_.code()) |
            ScratchBits::encode(scratch_.code());
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_CODEGEN_X64_H_