Optimize StoreIndexedComp on ia32&x64.

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 138 matching lines @@
   void AddExceptionHandler(intptr_t try_index, intptr_t pc_offset);
   void AddCurrentDescriptor(PcDescriptors::Kind kind,
                             intptr_t cid,
                             intptr_t token_index,
                             intptr_t try_index);
   Label* AddDeoptStub(intptr_t deopt_id,
                       intptr_t deopt_token_index,
                       intptr_t try_index_,
                       DeoptReasonId reason,
                       Register reg1,
-                      Register reg2);
+                      Register reg2,
+                      Register reg3 = kNoRegister);
 
   void FinalizeExceptionHandlers(const Code& code);
   void FinalizePcDescriptors(const Code& code);
   void FinalizeStackmaps(const Code& code);
   void FinalizeVarDescriptors(const Code& code);
   void FinalizeComments(const Code& code);
 
   static const int kLocalsOffsetFromFP = (-1 * kWordSize);
 
  private:
@@ skipping 123 matching lines @@
   const DeoptReasonId reason_;
   GrowableArray<Register> registers_;
   Label entry_label_;
 
   DISALLOW_COPY_AND_ASSIGN(DeoptimizationStub);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_COMPILER_X64_H_