Simplify implementation of assignment-to-const checks

src/x64/full-codegen-x64.cc

 // Copyright 2012 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 1947 matching lines @@
   BinaryOpStub stub(op, mode);
   JumpPatchSite patch_site(masm_);    // unbound, signals no inlined smi code.
   CallIC(stub.GetCode(), RelocInfo::CODE_TARGET,
          expr->BinaryOperationFeedbackId());
   patch_site.EmitPatchInfo();
   context()->Plug(rax);
 }
 
 
 void FullCodeGenerator::EmitAssignment(Expression* expr) {
-  // Invalid left-hand sides are rewritten to have a 'throw
+  // Invalid left-hand sides are rewritten by the parser to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
     VisitForEffect(expr);
     return;
   }
 
   // Left-hand side can only be a property, a global or a (parameter or local)
   // slot.
   enum LhsKind { VARIABLE, NAMED_PROPERTY, KEYED_PROPERTY };
   LhsKind assign_type = VARIABLE;
@@ skipping 2539 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64