[S.P.] Don't draw frames of animated images that are offscreen

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index f5e859a4720a8f87dce35e4a1bd908f6355e92dc..1131ec6e0bd583c747c5c3135bf4b80f6ae3021e 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -1203,8 +1203,14 @@ void LayoutObject::invalidateTreeIfNeeded(const PaintInvalidationState& paintInv
     if (!shouldCheckForPaintInvalidation(paintInvalidationState))
         return;
 
-    invalidatePaintIfNeeded(paintInvalidationState, paintInvalidationState.paintInvalidationContainer());
-    clearPaintInvalidationState(paintInvalidationState);
+    PaintInvalidationReason reason = invalidatePaintIfNeeded(paintInvalidationState, paintInvalidationState.paintInvalidationContainer());
+    if (reason != PaintInvalidationDelayedFull) {
+        clearPaintInvalidationState(paintInvalidationState);
+    } else {
+        // Mark this object as needing paint invalidation again in the next frame, due to the request for delayed paint invalidation.
+        setShouldDoFullPaintInvalidation(reason);
+    }
+
     invalidatePaintOfSubtreesIfNeeded(paintInvalidationState);
 }
 
@@ -3109,7 +3115,7 @@ static PaintInvalidationReason documentLifecycleBasedPaintInvalidationReason(con
 void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reason)
 {
     // Only full invalidation reasons are allowed.
-    ASSERT(isFullPaintInvalidationReason(reason));
+    ASSERT(isFullPaintInvalidationReason(reason) || reason == PaintInvalidationDelayedFull);
 
     if (m_bitfields.fullPaintInvalidationReason() == PaintInvalidationNone) {
         if (reason == PaintInvalidationFull)
@@ -3117,9 +3123,9 @@ void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reas
         m_bitfields.setFullPaintInvalidationReason(reason);
     }
 
-    ASSERT(document().lifecycle().state() != DocumentLifecycle::InPaintInvalidation);
     frame()->page()->animator().scheduleVisualUpdate(); // In case that this is called outside of FrameView::updateLayoutAndStyleForPainting().
     markContainerChainForPaintInvalidation();
+    ASSERT(document().lifecycle().state() != DocumentLifecycle::InPaintInvalidation || reason == PaintInvalidationDelayedFull);

[esprehn, 2015/03/25 05:06:36]

This still can let in bugs with the bits, if you use a separate walk you don't
need to change any of the asserts.

[chrishtr, 2015/03/25 23:30:35]

Done.

 }
 
 void LayoutObject::setMayNeedPaintInvalidation()