This method lets scripts set the zeal level for garbage collection. You can get details on what this method does in JS_SetGCZeal. This method calls through to that thusly:
JS_SetGCZeal(<current context>, zeal, JS_DEFAULT_ZEAL_FREQ, false);
Syntax
Components.utils.setGCZeal(zeal);
Where zeal is the zeal value you wish to use. This method has no effect unless running in a debug build.