| Index: src/runtime.cc | 
| diff --git a/src/runtime.cc b/src/runtime.cc | 
| index a344b28e0a030bcfc2410849ad8fa5a65b26153e..39310123e48440d33e0f59bcd576aec2270cbdea 100644 | 
| --- a/src/runtime.cc | 
| +++ b/src/runtime.cc | 
| @@ -1780,6 +1780,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_RegExpInitializeObject) { | 
| ASSERT(args.length() == 5); | 
| CONVERT_ARG_CHECKED(JSRegExp, regexp, 0); | 
| CONVERT_ARG_CHECKED(String, source, 1); | 
| +  // If source is the empty string we set it to "(?:)" instead as | 
| +  // suggested by ECMA-262, 5th, section 15.10.4.1. | 
| +  if (source->length() == 0) source = isolate->heap()->query_colon_symbol(); | 
|  | 
| Object* global = args[2]; | 
| if (!global->IsTrue()) global = isolate->heap()->false_value(); | 
|  |