Added a simple dead code removal phase.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 2c3f2daebbf141c38b4ef2c1ce0f5caeb383c462..70a6a0533cdb558b7c2dba0dbfc1ceb96ef499bf 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1854,7 +1854,7 @@ void HLoadKeyedFastElement::PrintDataTo(StringStream* stream) {
 }
 
 
-bool HLoadKeyedFastElement::RequiresHoleCheck() {
+bool HLoadKeyedFastElement::RequiresHoleCheck() const {
   if (IsFastPackedElementsKind(elements_kind())) {
     return false;
   }
@@ -2090,7 +2090,7 @@ void HLoadGlobalCell::PrintDataTo(StringStream* stream) {
 }
 
 
-bool HLoadGlobalCell::RequiresHoleCheck() {
+bool HLoadGlobalCell::RequiresHoleCheck() const {
   if (details_.IsDontDelete() && !details_.IsReadOnly()) return false;
   for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
     HValue* use = it.value();