Revert of 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 28b8e8e34b3fc163bb6fcbb0e27cdf2679131cfa..64a05167218c7d4f2cd599e2ea07cec495f1d83b 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -6716,11 +6716,7 @@
   Handle<TypeFeedbackVector> feedback_vector() const {
     return feedback_vector_;
   }
-  bool HasVectorAndSlot() const {
-    DCHECK(!FLAG_vector_ics || initialization_state_ == MEGAMORPHIC ||
-           feedback_vector_.is_null());
-    return !feedback_vector_.is_null();
-  }
+  bool HasVectorAndSlot() const { return FLAG_vector_ics; }
   void SetVectorAndSlot(Handle<TypeFeedbackVector> vector,
                         FeedbackVectorICSlot slot) {
     DCHECK(FLAG_vector_ics);