Optimistically assume that elements IC only transition once.

src/elements-kind.h

Index: src/elements-kind.h
diff --git a/src/elements-kind.h b/src/elements-kind.h
index ab31a33ee74940f4af413556000686ec094478ba..3be7711a35cadd29c4b57a596185146e8f0c5f19 100644
--- a/src/elements-kind.h
+++ b/src/elements-kind.h
@@ -86,6 +86,17 @@ ElementsKind GetFastElementsKindFromSequenceIndex(int sequence_index);
 int GetSequenceIndexFromFastElementsKind(ElementsKind elements_kind);
 
 
+inline bool IsDictionaryElementsKind(ElementsKind kind) {
+  return kind == DICTIONARY_ELEMENTS;
+}
+
+
+inline bool IsExternalArrayElementsKind(ElementsKind kind) {
+  return kind >= FIRST_EXTERNAL_ARRAY_ELEMENTS_KIND &&
+      kind <= LAST_EXTERNAL_ARRAY_ELEMENTS_KIND;
+}
+
+
 inline bool IsFastElementsKind(ElementsKind kind) {
   ASSERT(FIRST_FAST_ELEMENTS_KIND == 0);
   return kind <= FAST_HOLEY_DOUBLE_ELEMENTS;