Add a FOUC painting test.

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index cdfa3a72851e8005b125f67f28d907238286c97d..3c4bbc39cf2ec2546c435aeaa4cc6a0f10dd76c8 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -108,6 +108,8 @@ using namespace HTMLNames;
 static const unsigned maxUpdateWidgetsIterations = 2;
 static const double resourcePriorityUpdateDelayAfterScroll = 0.250;
 
+static bool s_initialTrackAllPaintInvalidations = false;
+
 FrameView::FrameView(LocalFrame* frame)
     : m_frame(frame)
     , m_displayMode(WebDisplayModeBrowser)
@@ -206,7 +208,7 @@ void FrameView::reset()
     m_safeToPropagateScrollToParent = true;
     m_lastViewportSize = IntSize();
     m_lastZoomFactor = 1.0f;
-    m_isTrackingPaintInvalidations = false;
+    m_isTrackingPaintInvalidations = s_initialTrackAllPaintInvalidations;
     m_trackedPaintInvalidationRects.clear();
     m_lastPaintTime = 0;
     m_isPainting = false;
@@ -1654,14 +1656,6 @@ void FrameView::contentRectangleForPaintInvalidation(const IntRect& rectInConten
 {
     ASSERT(!m_frame->ownerLayoutObject());
 
-    if (m_isTrackingPaintInvalidations) {
-        m_trackedPaintInvalidationRects.append(contentsToFrame(rectInContent));
-        // FIXME: http://crbug.com/368518. Eventually, invalidateContentRectangleForPaint
-        // is going away entirely once all layout tests are FCM. In the short
-        // term, no code should be tracking non-composited FrameView paint invalidations.
-        RELEASE_ASSERT_NOT_REACHED();
-    }
-
     IntRect paintRect = rectInContent;
     if (clipsPaintInvalidations())
         paintRect.intersect(visibleContentRect());
@@ -2823,6 +2817,11 @@ IntPoint FrameView::convertFromContainingView(const IntPoint& parentPoint) const
     return parentPoint;
 }
 
+void FrameView::setInitialTracksPaintInvalidationsForUnitTestsOnly(bool trackPaintInvalidations)
+{
+    s_initialTrackAllPaintInvalidations = trackPaintInvalidations;
+}
+
 void FrameView::setTracksPaintInvalidations(bool trackPaintInvalidations)
 {
     if (trackPaintInvalidations == m_isTrackingPaintInvalidations)