Add EmitNamedStore and CallStoreIC(name, is_contextual) to x64 platform.

src/x64/codegen-x64.h

Index: src/x64/codegen-x64.h
===================================================================
--- src/x64/codegen-x64.h	(revision 5107)
+++ src/x64/codegen-x64.h	(working copy)
@@ -456,10 +456,15 @@
 
   // Support for compiling assignment expressions.
   void EmitSlotAssignment(Assignment* node);
+  void EmitNamedPropertyAssignment(Assignment* node);
 
   // Receiver is passed on the frame and not consumed.
   Result EmitNamedLoad(Handle<String> name, bool is_contextual);
 
+  // If the store is contextual, value is passed on the frame and consumed.
+  // Otherwise, receiver and value are passed on the frame and consumed.
+  Result EmitNamedStore(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.