Bug 1469769 - Part 3: css: Replace failing NS_NOTREACHED with NS_ERROR. r=heycam

I'm replacing non-failing calls to NS_NOTREACHED with MOZ_ASSERT_UNREACHABLE, but this SelectionManager assertion fails when running the Linux debug Web platform tests with e10s test-linux32/debug-web-platform-tests-reftests-e10s-6 W-e10s(Wr6). This assertion failure is bug 1221888.

Marionette  INFO    Testing http://web-platform.test:8000/css/CSS2/ui/outline-applies-to-005.xht == http://web-platform.test:8000/css/CSS2/reference/no-red-on-blank-page-ref.xht
###!!! ASSERTION: we should have saved a frame property: 'Error', file /builds/worker/workspace/build/src/layout/painting/nsCSSRendering.cpp, line 1038

This patch DOES NOT fix the cause of the assertion failure (a missing HyperTextAccessible). It just replaces this failing NS_NOTREACHED with NS_ERROR because I can't replace with a fatal MOZ_ASSERT_UNREACHABLE.

MozReview-Commit-ID: L26bu4agM6y

--HG--
extra : rebase_source : 9a4188719fe5069cfbec47ae5fae0632ae1d5ee8
extra : intermediate-source : 0a3f719dce16fa80d6ae1bb20a41570050847731
extra : source : aadc67658e679893808256f60c480efeed426bc1

layout/painting/nsCSSRendering.cpp

@@ -1037,7 +1037,9 @@ GetOutlineInnerRect(nsIFrame* aFrame)
     aFrame->GetProperty(nsIFrame::OutlineInnerRectProperty());
   if (savedOutlineInnerRect)
     return *savedOutlineInnerRect;
-  NS_NOTREACHED("we should have saved a frame property");
+
+  // FIXME bug 1221888
+  NS_ERROR("we should have saved a frame property");
   return nsRect(nsPoint(0, 0), aFrame->GetSize());
 }