Add Crankshaft support for smi-only elements

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index ca6da72b77fb6c26340023bd138c8d8c96466b8f..8b507c26b3fdff31a006418196bdd255c0997036 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -942,6 +942,11 @@ class HGraphBuilder: public AstVisitor {
       HValue* val,
       ElementsKind elements_kind,
       bool is_store);
+  HInstruction* BuildFastElementAccess(HValue* elements,
+                                       HValue* checked_key,
+                                       HValue* val,
+                                       ElementsKind elements_kind,
+                                       bool is_store);
 
   HInstruction* BuildMonomorphicElementAccess(HValue* object,
                                               HValue* key,