Attach a WebLayer to a frame element for out-of-process iframes.

Source/core/rendering/RenderLayerCompositor.cpp

Index: Source/core/rendering/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/RenderLayerCompositor.cpp b/Source/core/rendering/RenderLayerCompositor.cpp
index 49d77c94619a7d8472518a81ee73c804cc72a9a5..1878e29ce54fa433921e7432405d13ea921ada2a 100644
--- a/Source/core/rendering/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/RenderLayerCompositor.cpp
@@ -1673,6 +1673,9 @@ bool RenderLayerCompositor::requiresCompositingForFrame(RenderObject* renderer)
     if (!frameRenderer->requiresAcceleratedCompositing())
         return false;
 
+    if (frameRenderer->node() && frameRenderer->node()->isFrameOwnerElement() && toHTMLFrameOwnerElement(frameRenderer->node())->contentFrame() && toHTMLFrameOwnerElement(frameRenderer->node())->contentFrame()->remotePlatformLayer())
+        return true;
+
     // FIXME: this seems bogus. If we don't know the layout position/size of the frame yet, wouldn't that be handled elsehwere?
     m_needsToRecomputeCompositingRequirements = true;