[type-feedback-vector] Delete unused DiffersFrom().

BUG=

Review-Url: https://codereview.chromium.org/2686493002
Cr-Commit-Position: refs/heads/master@{#42991}

src/type-feedback-vector.cc

@@ -122,24 +122,6 @@ bool TypeFeedbackMetadata::SpecDiffersFrom(
   return false;
 }
 
-bool TypeFeedbackMetadata::DiffersFrom(
-    const TypeFeedbackMetadata* other_metadata) const {
-  if (other_metadata->slot_count() != slot_count()) {
-    return true;
-  }
-
-  int slots = slot_count();
-  for (int i = 0; i < slots;) {
-    FeedbackVectorSlot slot(i);
-    FeedbackVectorSlotKind kind = GetKind(slot);
-    int entry_size = TypeFeedbackMetadata::GetSlotSize(kind);
-    if (GetKind(slot) != other_metadata->GetKind(slot)) {
-      return true;
-    }
-    i += entry_size;
-  }
-  return false;
-}
 
 const char* TypeFeedbackMetadata::Kind2String(FeedbackVectorSlotKind kind) {
   switch (kind) {

src/type-feedback-vector.h

@@ -230,8 +230,6 @@ class TypeFeedbackMetadata : public FixedArray {
 
   bool SpecDiffersFrom(const FeedbackVectorSpec* other_spec) const;
 
-  bool DiffersFrom(const TypeFeedbackMetadata* other_metadata) const;
-
   inline bool is_empty() const;
 
   // Returns number of slots in the vector.