Bug 1439101 - Port bug 1431960 to TB: Forcibly construct the frame for browser to construct browser binding in preferences subdialog. r=jorgk

mail/components/preferences/subdialogs.js

@@ -71,6 +71,16 @@ SubDialog.prototype = {
   async open(aURL, aFeatures = null, aParams = null, aClosingCallback = null) {
     // Wait until frame is ready to prevent browser crash in tests
     await this._frameCreated;
+
+    if (!this._frame.contentWindow) {
+      // Given the binding constructor execution is asynchronous, and "load"
+      // event can be dispatched before the browser element is shown, the
+      // browser binding might not be constructed at this point.  Forcibly
+      // construct the frame and construct the binding.
+      // FIXME: Remove this (bug 1437247)
+      this._frame.getBoundingClientRect();
+    }
+
     // If we're open on some (other) URL or we're closing, open when closing has finished.
     if (this._openedURL || this._isClosing) {
       if (!this._isClosing) {
@@ -511,6 +521,12 @@ var gSubDialog = {
       return;
     }
 
+    if (this._dialogs.length == 0) {
+      // When opening the first dialog, show the dialog stack to make sure
+      // the browser binding can be constructed.
+      this._dialogStack.hidden = false;
+    }
+
     this._preloadDialog.open(aURL, aFeatures, aParams, aClosingCallback);
     this._dialogs.push(this._preloadDialog);
     this._preloadDialog = new SubDialog({template: this._dialogTemplate,
@@ -518,7 +534,6 @@ var gSubDialog = {
                                          id: this._nextDialogID++});
 
     if (this._dialogs.length == 1) {
-      this._dialogStack.hidden = false;
       this._ensureStackEventListeners();
     }
   },