Implement proposed new identity spec.

runtime/vm/flow_graph_compiler_x64.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_COMPILER_X64_H_
 #define VM_FLOW_GRAPH_COMPILER_X64_H_
 
 #ifndef VM_FLOW_GRAPH_COMPILER_H_
 #error Include flow_graph_compiler.h instead of flow_graph_compiler_x64.h.
 #endif
@@ skipping 141 matching lines @@
 
   void EmitDoubleCompareBranch(Condition true_condition,
                                XmmRegister left,
                                XmmRegister right,
                                BranchInstr* branch);
   void EmitDoubleCompareBool(Condition true_condition,
                              XmmRegister left,
                              XmmRegister right,
                              Register result);
 
+  void EmitEqualityRegConstCompare(Register reg,
+                                   const Object& obj,
+                                   bool needs_number_check);
+  void EmitEqualityRegRegCompare(Register left,
+                                 Register right,
+                                 bool needs_number_check);
   void EmitEqualityRegConstCompare(Register reg, const Object& obj);
   // Implement equality: if any of the arguments is null do identity check.
   // Fallthrough calls super equality.
   void EmitSuperEqualityCallPrologue(Register result, Label* skip_call);
 
   intptr_t StackSize() const;
 
   // Returns assembler label associated with the given block entry.
   Label* GetBlockLabel(BlockEntryInstr* block_entry) const;
 
@@ skipping 168 matching lines @@
   // that should be used when deoptimizing we store it in this variable.
   // In future AddDeoptStub should be moved out of the instruction template.
   Environment* pending_deoptimization_env_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_COMPILER_X64_H_