VectorICs: megamorphic keyed loads in crankshaft don't need a vector.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 8c42e021c663ccae9851729bcea3a6c8f592c45e..0e5e1b6a9bf12241c19aeb8c4bb366894688fce6 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6667,7 +6667,11 @@ class HLoadKeyedGeneric FINAL : public HTemplateInstruction<3> {
   Handle<TypeFeedbackVector> feedback_vector() const {
     return feedback_vector_;
   }
-  bool HasVectorAndSlot() const { return FLAG_vector_ics; }
+  bool HasVectorAndSlot() const {
+    DCHECK(!FLAG_vector_ics || initialization_state_ == MEGAMORPHIC ||
+           !feedback_vector_.is_null());
+    return !feedback_vector_.is_null();
+  }
   void SetVectorAndSlot(Handle<TypeFeedbackVector> vector,
                         FeedbackVectorICSlot slot) {
     DCHECK(FLAG_vector_ics);