Add fast paths for native RegExps in ES2015 subclass-aware code

src/js/harmony-unicode-regexps.js

Index: src/js/harmony-unicode-regexps.js
diff --git a/src/js/harmony-unicode-regexps.js b/src/js/harmony-unicode-regexps.js
index b24bbdf2c545975c7455588ebc5df7c902139716..16d06ba7e37c0a56f20c2fe4324edc0a18681a23 100644
--- a/src/js/harmony-unicode-regexps.js
+++ b/src/js/harmony-unicode-regexps.js
@@ -31,10 +31,9 @@ function RegExpGetUnicode() {
     }
     throw MakeTypeError(kRegExpNonRegExp, "RegExp.prototype.unicode");
   }
-  return !!REGEXP_UNICODE(this);
+  return TO_BOOLEAN(REGEXP_UNICODE(this));
 }
-%FunctionSetName(RegExpGetUnicode, "RegExp.prototype.unicode");
-%SetNativeFlag(RegExpGetUnicode);
+%SetForceInlineFlag(RegExpGetUnicode);
 
 utils.InstallGetter(GlobalRegExp.prototype, 'unicode', RegExpGetUnicode);