[turbofan] Refactor IsSame into NodeProperties.

src/compiler/node-properties.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_NODE_PROPERTIES_H_
 #define V8_COMPILER_NODE_PROPERTIES_H_
 
 #include "src/compiler/node.h"
 #include "src/compiler/types.h"
 #include "src/globals.h"
@@ skipping 105 matching lines @@
   // Collect the output-value projection for the given output index.
   static Node* FindProjection(Node* node, size_t projection_index);
 
   // Collect the branch-related projections from a node, such as IfTrue,
   // IfFalse, IfSuccess, IfException, IfValue and IfDefault.
   //  - Branch: [ IfTrue, IfFalse ]
   //  - Call  : [ IfSuccess, IfException ]
   //  - Switch: [ IfValue, ..., IfDefault ]
   static void CollectControlProjections(Node* node, Node** proj, size_t count);
 
+  // Checks if two nodes are the same, looking past {CheckHeapObject}.
+  static bool IsSame(Node* a, Node* b);
+
   // ---------------------------------------------------------------------------
   // Context.
 
   // Try to retrieve the specialization context from the given {node},
   // optionally utilizing the knowledge about the (outermost) function
   // {context}.
   static MaybeHandle<Context> GetSpecializationContext(
       Node* node, MaybeHandle<Context> context = MaybeHandle<Context>());
 
   // Walk up the context chain from the given {node} until we reduce the {depth}
@@ skipping 19 matching lines @@
 
  private:
   static inline bool IsInputRange(Edge edge, int first, int count);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_NODE_PROPERTIES_H_