Fix HCheckValue::Canonicalize wrt uninitialized HConstant unique.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index a35134952da753ee932fd104ee680e06f5173d2f..802c0d682561c8a564839d2354b4cc285c3074a0 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1539,7 +1539,7 @@ bool HCheckMaps::HandleSideEffectDominator(GVNFlag side_effect,
     HStoreNamedField* store = HStoreNamedField::cast(dominator);
     if (!store->has_transition() || store->object() != value()) return false;
     HConstant* transition = HConstant::cast(store->transition());
-    if (map_set_.Contains(transition->GetUnique())) {
+    if (map_set_.Contains(Unique<Map>::cast(transition->GetUnique()))) {
       DeleteAndReplaceWith(NULL);
       return true;
     }
@@ -1567,9 +1567,7 @@ void HCheckValue::PrintDataTo(StringStream* stream) {
 
 HValue* HCheckValue::Canonicalize() {
   return (value()->IsConstant() &&
-          HConstant::cast(value())->GetUnique() == object_)
-      ? NULL
-      : this;
+          HConstant::cast(value())->EqualsUnique(object_)) ? NULL : this;
 }