Bug 1250880 - remove fat-fingered (and unneeded) css rule r=dtownsend

MozReview-Commit-ID: 7W1vW82BB9l

--HG--
extra : transplant_source : P%FE%87%078%A8%D7g%98_%22%87%CE%05%22m%EB%CD%28%10

toolkit/themes/shared/extensions/extensions.inc.css

@@ -137,7 +137,6 @@
 
 button.warning {
   list-style-image: url("chrome://mozapps/skin/extensions/alerticon-warning.svg");
-  list-stye-position: inside;
 }