Why was this checked in w/o review and super review? This setting is causing the JS console to be filled with insignificant warnings that do no other good than hiding real errors, taking out the pref since this is hindering development. If you have issues with this, feel free to contact me.

modules/libpref/src/debug-developer.js

@@ -20,4 +20,3 @@
  * Contributor(s): 
  */
 
-pref("javascript.options.strict", true);