Bug 1352183 - Preserve lazy browsers' lazy state when closing the window. r=dao

browser/base/content/tabbrowser.xml

@@ -2078,6 +2078,13 @@
               let getter;
               let setter;
               switch (name) {
+                case "permitUnload":
+                  getter = () => {
+                    return function() {
+                      return { permitUnload: true, timedOut: false };
+                    };
+                  };
+                  break;
                 default:
                   getter = () => {
                     this._insertBrowser(aTab);
@@ -5288,15 +5295,20 @@
                                                        browser.getAttribute("usercontextid") || 0);
               delete browser.registeredOpenURI;
             }
+
             let filter = this._tabFilters.get(tab);
-            let listener = this._tabListeners.get(tab);
+            if (filter) {
+              browser.webProgress.removeProgressListener(filter);
 
-            browser.webProgress.removeProgressListener(filter);
-            filter.removeProgressListener(listener);
-            listener.destroy();
+              let listener = this._tabListeners.get(tab);
+              if (listener) {
+                filter.removeProgressListener(listener);
+                listener.destroy();
+              }
 
-            this._tabFilters.delete(tab);
-            this._tabListeners.delete(tab);
+              this._tabFilters.delete(tab);
+              this._tabListeners.delete(tab);
+            }
           }
           const nsIEventListenerService =
             Components.interfaces.nsIEventListenerService;

browser/components/sessionstore/TabStateFlusher.jsm

@@ -84,6 +84,11 @@ var TabStateFlusherInternal = {
    * all the latest data.
    */
   flush(browser) {
+    let tabbrowser = browser.ownerGlobal.gBrowser;
+    if (!tabbrowser.getTabForBrowser(browser).linkedPanel) {
+      return;
+    }
+
     let id = ++this._lastRequestID;
     let mm = browser.messageManager;
     mm.sendAsyncMessage("SessionStore:flush", {id});