compositor-worker: Force elements to grow a layer when a CompositorProxy is created.

Source/core/layout/LayoutBox.cpp

Index: Source/core/layout/LayoutBox.cpp
diff --git a/Source/core/layout/LayoutBox.cpp b/Source/core/layout/LayoutBox.cpp
index 6503f5b0e902c4fcbf1255c723d166d675e9993f..db0fa2c499491d7a714e23b742d26575ba93691c 100644
--- a/Source/core/layout/LayoutBox.cpp
+++ b/Source/core/layout/LayoutBox.cpp
@@ -112,7 +112,7 @@ DeprecatedPaintLayerType LayoutBox::layerTypeRequired() const
     // hasAutoZIndex only returns true if the element is positioned or a flex-item since
     // position:static elements that are not flex-items get their z-index coerced to auto.
     if (isPositioned() || createsGroup() || hasClipPath() || hasTransformRelatedProperty()
-        || hasHiddenBackface() || hasReflection() || style()->specifiesColumns()
+        || style()->hasCompositorProxy() || hasHiddenBackface() || hasReflection() || style()->specifiesColumns()
         || !style()->hasAutoZIndex() || style()->shouldCompositeForCurrentAnimations())
         return NormalDeprecatedPaintLayer;