Firefox and Safari both allow calling regular expression objects as...

src/execution.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 146 matching lines @@
   return result;
 }
 
 
 Handle<Object> Execution::GetFunctionDelegate(Handle<Object> object) {
   ASSERT(!object->IsJSFunction());
 
   // If you return a function from here, it will be called when an
   // attempt is made to call the given object as a function.
 
-  // The regular expression code here is really meant more as an
-  // example than anything else. KJS does not support calling regular
-  // expressions as functions, but SpiderMonkey does.
-  if (FLAG_call_regexp) {
-    bool is_regexp =
-        object->IsHeapObject() &&
-        (HeapObject::cast(*object)->map()->constructor() ==
-         *Top::regexp_function());
+  // Regular expressions can be called as functions in both Firefox
+  // and Safari so we allow it too.
+  bool is_regexp =
+      object->IsHeapObject() &&
+      (HeapObject::cast(*object)->map()->constructor() ==
+       *Top::regexp_function());
 
-    if (is_regexp) {
-      Handle<String> exec = Factory::exec_symbol();
-      return Handle<Object>(object->GetProperty(*exec));
-    }
+  if (is_regexp) {
+    Handle<String> exec = Factory::exec_symbol();
+    return Handle<Object>(object->GetProperty(*exec));
   }
 
   // Objects created through the API can have an instance-call handler
   // that should be used when calling the object as a function.
   if (object->IsHeapObject() &&
       HeapObject::cast(*object)->map()->has_instance_call_handler()) {
     return Handle<JSFunction>(
         Top::global_context()->call_as_function_delegate());
   }
 
@@ skipping 454 matching lines @@
   // All allocation spaces other than NEW_SPACE have the same effect.
   Heap::CollectAllGarbage();
   return v8::Undefined();
 }
 
 
 static GCExtension kGCExtension;
 v8::DeclareExtension kGCExtensionDeclaration(&kGCExtension);
 
 } }  // namespace v8::internal