All calls to JavaScript methods fail, with the JavaScript Console showing "TypeError: Object function alert() { [native code] } (result of expression alert) does not allow calls."
Looks like an incomplete checkin of the function names patch from bug 6279 caused this.
If I apply the lookup.h part of the patch from bug 6279 instead of the last-minute change that was checked in in r12911, it fixes the bug. The last-minute change was to derive function implementations from InternalFunctionImp instead of HashEntryFunction, but the latter doesn't return true from implementsCall().
Fixing it.