Attempt to do direct class comparison for type checks using CHA.

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 280 matching lines @@
     kTestTypeThreeArgs,
   };
 
   RawSubtypeTestCache* GenerateCallSubtypeTestStub(TypeTestStubKind test_kind,
                                                    Register instance_reg,
                                                    Register type_arguments_reg,
                                                    Register temp_reg,
                                                    Label* is_instance_lbl,
                                                    Label* is_not_instance_lbl);
 
+  // Returns true if checking against this type is a direct class id comparison.
+  bool TypeCheckAsClassEquality(const AbstractType& type);
+
   void GenerateBoolToJump(Register bool_reg, Label* is_true, Label* is_false);
 
   void CopyParameters();
 
   void GenerateInlinedGetter(intptr_t offset);
   void GenerateInlinedSetter(intptr_t offset);
 
   // Map a block number in a forward iteration into the block number in the
   // corresponding reverse iteration.  Used to obtain an index into
   // block_order for reverse iterations.
@@ skipping 35 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_