Adding ThisFunction expression to top-level compiler.

src/x64/fast-codegen-x64.cc

 // Copyright 2009 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 1636 matching lines @@
       __ PushRoot(Heap::kFalseValueRootIndex);
       __ jmp(saved_false);
       break;
   }
   true_label_ = saved_true;
   false_label_ = saved_false;
   // Convert current context to test context: End post-test code.
 }
 
 
+void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) {
+  __ movq(rax, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
+  Move(expr->context(), rax);
+}
+
+
 #undef __
 
 
 } }  // namespace v8::internal