Synchronize ChromeUtils change from Bug 1431533 (#5282)

Author: juliandescottes

assets/panel/index.html

@@ -20,7 +20,7 @@
     <script type="application/javascript"
             src="chrome://devtools/content/shared/theme-switching.js"></script>
     <script type="text/javascript">
-      const { BrowserLoader } = Components.utils.import("resource://devtools/client/shared/browser-loader.js", {});
+      const { BrowserLoader } = ChromeUtils.import("resource://devtools/client/shared/browser-loader.js", {});
       const { require } = BrowserLoader({
         baseURI: "resource://devtools/client/debugger/new/",
         window,