Simple support for const variables in Crankshaft....

src/x64/lithium-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1616 matching lines @@
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoThrow(HThrow* instr) {
   LOperand* value = UseFixed(instr->value(), rax);
   return MarkAsCall(new LThrow(value), instr);
 }
 
 
+LInstruction* LChunkBuilder::DoUseConst(HUseConst* instr) {
+  return NULL;
+}
+
+
 LInstruction* LChunkBuilder::DoForceRepresentation(HForceRepresentation* bad) {
   // All HForceRepresentation instructions should be eliminated in the
   // representation change phase of Hydrogen.
   UNREACHABLE();
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   Representation from = instr->from();
@@ skipping 572 matching lines @@
   LOperand* key = UseOrConstantAtStart(instr->key());
   LOperand* object = UseOrConstantAtStart(instr->object());
   LIn* result = new LIn(key, object);
   return MarkAsCall(DefineFixed(result, rax), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64