Bug 1539757 - fix trying to initialize XBL bindings while the prompt is still hidden, r=bgrins

Differential Revision: https://phabricator.services.mozilla.com/D25390

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

browser/base/content/browser.js

@@ -8369,6 +8369,8 @@ TabModalPromptBox.prototype = {
     if (prompts.length) {
       let prompt = prompts[prompts.length - 1];
       prompt.element.hidden = false;
+      // Because we were hidden before, this won't have been possible, so do it now:
+      prompt.ensureXBLBindingAttached();
       prompt.Dialog.setDefaultFocus();
     } else {
       browser.removeAttribute("tabmodalPromptShowing");

browser/base/content/test/tabPrompts/browser_multiplePrompts.js

@@ -8,20 +8,21 @@
  * the oldest one.
  */
 add_task(async function() {
-  const PROMPTCOUNT = 5;
+  const PROMPTCOUNT = 9;
 
-  let contentScript = function() {
-    var i = 5; // contentScript has no access to PROMPTCOUNT.
+  let contentScript = function(MAX_PROMPT) {
+    var i = MAX_PROMPT;
+    let fns = ["alert", "prompt", "confirm"];
     window.addEventListener("message", function() {
       i--;
       if (i) {
         window.postMessage("ping", "*");
       }
-      alert("Alert countdown #" + i);
+      window[fns[i % 3]](fns[i % 3] + " countdown #" + i);
     });
     window.postMessage("ping", "*");
   };
-  let url = "data:text/html,<script>(" + encodeURIComponent(contentScript.toSource()) + ")();</script>";
+  let url = "data:text/html,<script>(" + encodeURIComponent(contentScript.toSource()) + ")(" + PROMPTCOUNT + ");</script>";
 
   let promptsOpenedPromise = new Promise(function(resolve) {
     let unopenedPromptCount = PROMPTCOUNT;
@@ -48,7 +49,8 @@ add_task(async function() {
     let i = 0;
     for (let promptElement of promptElements) {
       let prompt = tab.linkedBrowser.tabModalPromptBox.prompts.get(promptElement);
-      is(prompt.Dialog.args.text, "Alert countdown #" + i, "The #" + i + " alert should be labelled as such.");
+      let expectedType = ["alert", "prompt", "confirm"][i % 3];
+      is(prompt.Dialog.args.text, expectedType + " countdown #" + i, "The #" + i + " alert should be labelled as such.");
       if (i !== promptElementsCount) {
         is(prompt.element.hidden, true, "This prompt should be hidden.");
         i++;

browser/modules/RemotePrompt.jsm

@@ -80,6 +80,7 @@ var RemotePrompt = {
       // there's other stuff in nsWindowWatcher::OpenWindowInternal
       // that we might need to do here as well.
     } catch (ex) {
+      Cu.reportError(ex);
       onPromptClose(true);
     }
   },

toolkit/components/prompts/src/CommonDialog.jsm

@@ -162,6 +162,7 @@ CommonDialog.prototype = {
         else
             button.setAttribute("default", "true");
 
+        if (!this.ui.promptContainer.hidden) {
             // For tab prompts, we will need to ensure its content bindings are attached.
             if (!xulDialog) {
                 this.ui.prompt.ensureXBLBindingAttached();
@@ -169,6 +170,7 @@ CommonDialog.prototype = {
 
             // Set default focus / selection.
             this.setDefaultFocus(true);
+        }
 
         if (this.args.enableDelay) {
             this.delayHelper = new EnableDelayHelper({