Make Variable::is_this always return the correct value

src/full-codegen/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 2930 matching lines @@
         VisitForStackValue(property->obj());
         VisitForStackValue(property->key());
         CallRuntimeWithOperands(is_strict(language_mode())
                                     ? Runtime::kDeleteProperty_Strict
                                     : Runtime::kDeleteProperty_Sloppy);
         context()->Plug(rax);
       } else if (proxy != NULL) {
         Variable* var = proxy->var();
         // Delete of an unqualified identifier is disallowed in strict mode but
         // "delete this" is allowed.
-        bool is_this = var->HasThisName(isolate());
+        bool is_this = var->is_this();
         DCHECK(is_sloppy(language_mode()) || is_this);
         if (var->IsUnallocatedOrGlobalSlot()) {
           __ movp(rax, NativeContextOperand());
           __ Push(ContextOperand(rax, Context::EXTENSION_INDEX));
           __ Push(var->name());
           __ CallRuntime(Runtime::kDeleteProperty_Sloppy);
           context()->Plug(rax);
         } else if (var->IsStackAllocated() || var->IsContextSlot()) {
           // Result of deleting non-global variables is false.  'this' is
           // not really a variable, though we implement it as one.  The
@@ skipping 700 matching lines @@
   DCHECK_EQ(
       isolate->builtins()->OnStackReplacement()->entry(),
       Assembler::target_address_at(call_target_address, unoptimized_code));
   return ON_STACK_REPLACEMENT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64