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

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 8634a2bbd16320799487ebf9890f24bf2496cd60..d9cce736255afdd658fff93916eec9a03d38e77b 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6124,10 +6124,9 @@ MaybeLocal<v8::RegExp> v8::RegExp::New(Local<Context> context,
                                        Local<String> pattern, Flags flags) {
   PREPARE_FOR_EXECUTION(context, "RegExp::New", RegExp);
   Local<v8::RegExp> result;
-  has_pending_exception =
-      !ToLocal<RegExp>(i::Execution::NewJSRegExp(Utils::OpenHandle(*pattern),
-                                                 RegExpFlagsToString(flags)),
-                       &result);
+  has_pending_exception = !ToLocal<RegExp>(
+      i::JSRegExp::New(Utils::OpenHandle(*pattern), RegExpFlagsToString(flags)),
+      &result);
   RETURN_ON_FAILED_EXECUTION(RegExp);
   RETURN_ESCAPED(result);
 }