Recognize special comparisons via pattern matching on the hydrogen graph, 2nd attempt.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
===================================================================
--- src/hydrogen-instructions.h	(revision 9687)
+++ src/hydrogen-instructions.h	(working copy)
@@ -2287,6 +2287,7 @@
   }
 
   virtual bool EmitAtUses() { return !representation().IsDouble(); }
+  virtual HValue* Canonicalize();
   virtual void PrintDataTo(StringStream* stream);
   virtual HType CalculateInferredType();
   bool IsInteger() const { return handle_->IsSmi(); }
@@ -4159,6 +4160,7 @@
   HValue* context() { return OperandAt(0); }
   HValue* value() { return OperandAt(1); }
 
+  virtual HValue* Canonicalize();
   virtual void PrintDataTo(StringStream* stream);
 
   virtual Representation RequiredInputRepresentation(int index) {