Fixing issue 1898 (using HChange outside the insert-representation-changes phase).

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index d98fb3b7f07f28af3fc066478b4b7da8e9649b88..887e80afc43789725a11b0bea7d78d5bf13f42cd 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 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:
@@ -806,6 +806,11 @@ HValue* HBitwise::Canonicalize() {
 }
 
 
+HValue* HChange::Canonicalize() {
+  return (from().Equals(to())) ? value() : this;
+}
+
+
 void HTypeof::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
 }