Add EmitSlotAssignment to x64 platform.

Review URL: http://codereview.chromium.org/2878042

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5107 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/codegen-x64.h

@@ -454,6 +454,9 @@ class CodeGenerator: public AstVisitor {
   // 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);