Bug 1516130 - Accel+K shouldn't focus and modify the read-only address bar in popups. r=mak

Differential Revision: https://phabricator.services.mozilla.com/D15260

--HG--
extra : moz-landing-system : lando

browser/base/content/browser.js

@@ -3982,13 +3982,14 @@ const BrowserSearch = {
   },
 
   /**
-   * Gives focus to the search bar, if it is present on the toolbar, or loads
-   * the default engine's search form otherwise. For Mac, opens a new window
-   * or focuses an existing window, if necessary.
+   * Focuses the search bar if present on the toolbar, or the address bar,
+   * putting it in search mode. Will do so in an existing non-popup browser
+   * window or open a new one if necessary.
    */
   webSearch: function BrowserSearch_webSearch() {
-    if (window.location.href != AppConstants.BROWSER_CHROME_URL) {
-      var win = getTopWin();
+    if (window.location.href != AppConstants.BROWSER_CHROME_URL ||
+        gURLBar.readOnly) {
+      let win = getTopWin(true);
       if (win) {
         // If there's an open browser window, it should handle this command
         win.focus();