Simple support for const variables in Crankshaft....

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
===================================================================
--- src/hydrogen-instructions.h	(revision 6080)
+++ src/hydrogen-instructions.h	(working copy)
@@ -129,6 +129,7 @@
 //       HCheckPrototypeMaps
 //       HCheckSmi
 //       HDeleteProperty
+//       HInitConst
 //       HLoadElements
 //         HTypeofIs
 //       HLoadNamedField
@@ -207,6 +208,7 @@
   V(GlobalObject)                              \
   V(GlobalReceiver)                            \
   V(Goto)                                      \
+  V(InitConst)                                 \
   V(InstanceOf)                                \
   V(IsNull)                                    \
   V(IsObject)                                  \
@@ -961,6 +963,13 @@
 };
 
 
+class HInitConst: public HUnaryOperation {
+ public:
+  explicit HInitConst(HValue* old_value) : HUnaryOperation(old_value) { }
+  DECLARE_CONCRETE_INSTRUCTION(InitConst, "init_const")
+};
+
+
 class HChange: public HUnaryOperation {
  public:
   HChange(HValue* value,