[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..40bd6bda06659c3cdc866565a5d609e9fba58c21 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();
+    }
+
     invalidatePaintOfSubtreesIfNeeded(paintInvalidationState);
 }
 
@@ -3117,7 +3123,6 @@ void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reas
         m_bitfields.setFullPaintInvalidationReason(reason);
     }
 
-    ASSERT(document().lifecycle().state() != DocumentLifecycle::InPaintInvalidation);

[esprehn, 2015/03/20 06:52:32]

Are you sure this is safe? Calling markContainerChainForPaintInvalidation inside
paint invalidation seems like it would leave dirty bits in the tree.

[chrishtr, 2015/03/20 16:44:45]

Good point, this assert is still valuable for preventing other bad use. I'll
adjust it.

     frame()->page()->animator().scheduleVisualUpdate(); // In case that this is called outside of FrameView::updateLayoutAndStyleForPainting().
     markContainerChainForPaintInvalidation();
 }