[regexp] Extract code to regexp-utils.{h,cc}

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 1013d87119408b8cbdd835dbc06f2f1d64a09a19..7bb3ca2ecbc5184cf619ebcb516922181c95e63b 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1376,10 +1376,6 @@ class Object {
       Isolate* isolate, Handle<Object> object, uint32_t index,
       Handle<Object> value, LanguageMode language_mode);
 
-  // ES#sec-isregexp IsRegExp ( argument )
-  // Includes checking of the mach property as per section 7.2.8 IsRegExp.
-  static Maybe<bool> IsRegExp(Isolate* isolate, Handle<Object> object);
-
   // Returns the permanent hash code associated with this object. May return
   // undefined if not yet created.
   Object* GetHash();