[Interpreter] Optimize equality check with null/undefined with a check on the map.

src/compiler/js-operator.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_JS_OPERATOR_H_
 #define V8_COMPILER_JS_OPERATOR_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/globals.h"
 #include "src/runtime/runtime.h"
@@ skipping 413 matching lines @@
   explicit JSOperatorBuilder(Zone* zone);
 
   const Operator* Equal(CompareOperationHint hint);
   const Operator* NotEqual(CompareOperationHint hint);
   const Operator* StrictEqual(CompareOperationHint hint);
   const Operator* StrictNotEqual(CompareOperationHint hint);
   const Operator* LessThan(CompareOperationHint hint);
   const Operator* GreaterThan(CompareOperationHint hint);
   const Operator* LessThanOrEqual(CompareOperationHint hint);
   const Operator* GreaterThanOrEqual(CompareOperationHint hint);
+  const Operator* IsUndetectable();
 
   const Operator* BitwiseOr(BinaryOperationHint hint);
   const Operator* BitwiseXor(BinaryOperationHint hint);
   const Operator* BitwiseAnd(BinaryOperationHint hint);
   const Operator* ShiftLeft(BinaryOperationHint hint);
   const Operator* ShiftRight(BinaryOperationHint hint);
   const Operator* ShiftRightLogical(BinaryOperationHint hint);
   const Operator* Add(BinaryOperationHint hint);
   const Operator* Subtract(BinaryOperationHint hint);
   const Operator* Multiply(BinaryOperationHint hint);
@@ skipping 98 matching lines @@
   Zone* const zone_;
 
   DISALLOW_COPY_AND_ASSIGN(JSOperatorBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_OPERATOR_H_