Hydrogen code stubs for vector-based ICs.

src/type-feedback-vector.cc

Index: src/type-feedback-vector.cc
diff --git a/src/type-feedback-vector.cc b/src/type-feedback-vector.cc
index 0e78358d949df687b688bc1e9edb37883c9826f9..7d575e2477d1d8c3a2342d73597ab844e7ef1f26 100644
--- a/src/type-feedback-vector.cc
+++ b/src/type-feedback-vector.cc
@@ -98,6 +98,10 @@ Handle<TypeFeedbackVector> TypeFeedbackVector::Allocate(
   }
   array->set(kWithTypesIndex, Smi::FromInt(0));
   array->set(kGenericCountIndex, Smi::FromInt(0));
+  // Fill the indexes with zeros.
+  for (int i = 0; i < index_count; i++) {
+    array->set(kReservedIndexCount + i, Smi::FromInt(0));
+  }
 
   // Ensure we can skip the write barrier
   Handle<Object> uninitialized_sentinel = UninitializedSentinel(isolate);
@@ -258,8 +262,6 @@ InlineCacheState KeyedLoadICNexus::StateFromFeedback() const {
     return UNINITIALIZED;
   } else if (feedback == *vector()->PremonomorphicSentinel(isolate)) {
     return PREMONOMORPHIC;
-  } else if (feedback == *vector()->MegamorphicSentinel(isolate)) {
-    return MEGAMORPHIC;
   } else if (feedback == *vector()->GenericSentinel(isolate)) {
     return GENERIC;
   } else if (feedback->IsFixedArray()) {
@@ -322,11 +324,6 @@ void KeyedLoadICNexus::ConfigureGeneric() {
 }
 
 
-void KeyedLoadICNexus::ConfigureMegamorphic() {
-  SetFeedback(*vector()->MegamorphicSentinel(GetIsolate()), SKIP_WRITE_BARRIER);
-}
-
-
 void LoadICNexus::ConfigureMegamorphic() {
   SetFeedback(*vector()->MegamorphicSentinel(GetIsolate()), SKIP_WRITE_BARRIER);
 }