Introduce a BuiltinsConstructStub that sets up new.target and does a [[call]] per ES6 9.3.2

src/regexp/jsregexp.cc

Index: src/regexp/jsregexp.cc
diff --git a/src/regexp/jsregexp.cc b/src/regexp/jsregexp.cc
index b940bb74b118addaa759af38bb61e61ff050b402..224a27ddbbf7c8a374e9672f56188359bc9d0ca6 100644
--- a/src/regexp/jsregexp.cc
+++ b/src/regexp/jsregexp.cc
@@ -51,16 +51,6 @@
 namespace v8 {
 namespace internal {
 
-MaybeHandle<Object> RegExpImpl::CreateRegExpLiteral(
-    Handle<JSFunction> constructor,
-    Handle<String> pattern,
-    Handle<String> flags) {
-  // Call the construct code with 2 arguments.
-  Handle<Object> argv[] = { pattern, flags };
-  return Execution::New(constructor, arraysize(argv), argv);
-}
-
-
 MUST_USE_RESULT
 static inline MaybeHandle<Object> ThrowRegExpException(
     Handle<JSRegExp> re, Handle<String> pattern, Handle<String> error_text) {