Fix additional spec violations wrt RegExp.lastIndex.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 958e1efd659f27fab037640f4fffb0f8672b7d55..975fdf8d85a46b98a7d3715c09b798444efaec83 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6622,8 +6622,6 @@ class JSRegExp: public JSObject {
   inline void SetDataAtUnchecked(int index, Object* value, Heap* heap);
   inline Type TypeTagUnchecked();
 
-  static inline void ResetLastIndex(Isolate* isolate, Handle<JSRegExp> regexp);
-
   static int code_index(bool is_ascii) {
     if (is_ascii) {
       return kIrregexpASCIICodeIndex;