Bug 1676292 - Stop importing common.css in extensions.xhtml. r=robwu

Differential Revision: https://phabricator.services.mozilla.com/D96480

toolkit/mozapps/extensions/content/extensions.js

@@ -6,7 +6,6 @@
 
 /* import-globals-from ../../../content/customElements.js */
 /* import-globals-from aboutaddonsCommon.js */
-/* globals ProcessingInstruction */
 /* exported loadView */
 
 const { AddonManager } = ChromeUtils.import(
@@ -30,11 +29,6 @@ Object.defineProperty(this, "gIsInitializing", {
 });
 
 function initialize(event) {
-  // XXXbz this listener gets _all_ load events for all nodes in the
-  // document... but relies on not being called "too early".
-  if (event.target instanceof ProcessingInstruction) {
-    return;
-  }
   document.removeEventListener("load", initialize, true);
 
   if (!isDiscoverEnabled()) {

toolkit/mozapps/extensions/content/extensions.xhtml

@@ -3,8 +3,6 @@
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
-<?xml-stylesheet href="chrome://global/skin/in-content/common.css"?>
-
 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:xhtml="http://www.w3.org/1999/xhtml"
         csp="default-src chrome:; frame-src chrome:; object-src 'none'"