Fix paint property under-invalidation of CSS clip on resize

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 3d8e6aff6c568f4f62405a253c1bb7be86cca4a2..456e411cbfb3a0d7b3ddef0e74bf1e6bd0209937 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -1735,6 +1735,10 @@ void LayoutBox::sizeChanged() {
       // overflowClipRect(). The border box rect's size equals the frame rect's
       // size so we trigger a paint property update when the frame rect changes.
       setNeedsPaintPropertyUpdate();
+    } else if (hasClip()) {

[chrishtr, 2017/02/28 00:11:18]

Is this needed for clip-path as well?

[Xianzhu, 2017/02/28 00:17:20]

We seem not to support clip-path in paint property tree for now. Should we?

[trchen, 2017/02/28 00:43:28]

Thanks for the heads up! Yea, I think this will be needed for clip-path as well,
and definitely is needed for masks. (Because masks implicitly create a clip,
which is implemented by clip node.)

I think it makes sense to match
LayoutBox::paintedOutputOfObjectHasNoEffectRegardlessOfSize().
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/layout/La...

+      // The used value of CSS clip may depend on size of the box, e.g. for
+      // clip: rect(auto auto auto -5px).
+      setNeedsPaintPropertyUpdate();
     } else if (styleRef().hasTransform() || styleRef().hasPerspective()) {
       // Relative lengths (e.g., percentage values) in transform, perspective,
       // transform-origin, and perspective-origin can depend on the size of the