Bug 915962 - Part 3: Do not crash when pressing the space bar without having an element focused; r=roc

dom/xbl/nsXBLPrototypeHandler.cpp

@@ -478,7 +478,7 @@ nsXBLPrototypeHandler::DispatchXBLCommand(EventTarget* aTarget, nsIDOMEvent* aEv
     }
 
     // If the focus is in an editable region, don't scroll.
-    if (focusedContent->IsEditable()) {
+    if (focusedContent && focusedContent->IsEditable()) {
       return NS_OK;
     }
 

editor/libeditor/tests/test_bug915962.html

@@ -67,7 +67,22 @@ function startTest() {
   win.close();
   cwu.restoreNormalRefresh();
 
-  SimpleTest.finish();
+  win = window.open("file_bug915962.html", "_blank",
+                    "width=600,height=600,scrollbars=yes");
+  cwu = SpecialPowers.getDOMWindowUtils(win);
+  SimpleTest.waitForFocus(function() {
+    is(win.scrollY, 0, "Sanity check");
+    synthesizeKey(" ", {}, win);
+
+    step();
+
+    isnot(win.scrollY, 0, "Page is scrolled down without crashing");
+
+    win.close();
+    cwu.restoreNormalRefresh();
+
+    SimpleTest.finish();
+  }, win);
 }
 </script>
 </pre>