[turbofan] Properly implement %_ClassOf intrinsic.

src/code-stub-assembler.h

 // Copyright 2016 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_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 1121 matching lines @@
   // differs from positive zero.
   // Unlike Equal and StrictEqual, returns a value suitable for use in Branch
   // instructions, e.g. Branch(SameValue(...), &label).
   Node* SameValue(Node* lhs, Node* rhs, Node* context);
 
   Node* HasProperty(
       Node* object, Node* key, Node* context,
       Runtime::FunctionId fallback_runtime_function_id = Runtime::kHasProperty);
   Node* ForInFilter(Node* key, Node* object, Node* context);
 
+  Node* ClassOf(Node* object);
+
   Node* Typeof(Node* value, Node* context);
 
   Node* GetSuperConstructor(Node* value, Node* context);
 
   Node* InstanceOf(Node* object, Node* callable, Node* context);
 
   // Debug helpers
   Node* IsDebugActive();
 
   // TypedArray/ArrayBuffer helpers
@@ skipping 132 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_