Check for null focusedWindow in case of full-page plugins b=304243 r=IanN sr=jag

xpfe/browser/resources/content/navigator.js

@@ -279,7 +279,7 @@ function getContentAreaFrameCount()
 function contentAreaFrameFocus()
 {
   const focusedWindow = document.commandDispatcher.focusedWindow;
-  if (focusedWindow.top == window.content) {
+  if (focusedWindow && focusedWindow.top == window.content) {
     gFocusedURL = focusedWindow.location.href;
     gFocusedDocument = focusedWindow.document;
   }

xpfe/communicator/resources/content/tasksOverlay.js

@@ -86,7 +86,13 @@ function toJavaConsole()
 
 function toOpenWindow( aWindow )
 {
-  aWindow.document.commandDispatcher.focusedWindow.focus();
+  try {
+    // Try to focus the previously focused window e.g. message compose body
+    aWindow.document.commandDispatcher.focusedWindow.focus();
+  } catch (e) {
+    // e.g. full-page plugin or non-XUL document; just raise the top window
+    aWindow.focus();
+  }
 }
 
 function toOpenWindowByType( inType, uri )

xpfe/global/resources/content/bindings/tabbrowser.xml

@@ -556,7 +556,7 @@
               var focusedWindow = document.commandDispatcher.focusedWindow;
               var saveFocus = false;
 
-              if (focusedWindow.top == window.content) {
+              if (focusedWindow && focusedWindow.top == window.content) {
                 saveFocus = true;
               } else {
                 var contentWindow = window;