Bug 712130 - Simplify focus stealing prevention for autofocus. r=bz

Remove redundant check already implied by earlier condition: If the focus
manager's focused content is in our document, all parent windows including the
root window must have their focused node set to non-null.

MozReview-Commit-ID: CryGb6mfczK

--HG--
extra : rebase_source : c16e73b159be0fd82da624ab971f6b026eb01ae6

dom/base/nsDocument.cpp

@@ -9982,27 +9982,14 @@ public:
 
   NS_IMETHOD Run() override
   {
-    nsFocusManager* fm = nsFocusManager::GetFocusManager();
-    if (!fm) {
-      return NS_ERROR_NULL_POINTER;
-    }
-
-    nsIDocument* document = mElement->OwnerDoc();
-
     // Don't steal focus from the user.
     if (mRootWindow->GetFocusedNode()) {
       return NS_OK;
     }
 
-    // If something is focused in the same document, ignore autofocus.
-    if (!fm->GetFocusedContent() ||
-        fm->GetFocusedContent()->OwnerDoc() != document) {
-      mozilla::ErrorResult rv;
-      mElement->Focus(rv);
-      return rv.StealNSResult();
-    }
-
-    return NS_OK;
+    mozilla::ErrorResult rv;
+    mElement->Focus(rv);
+    return rv.StealNSResult();
   }
 private:
   nsCOMPtr<Element> mElement;