Plumb whether or not a frame is in shadow DOM to the embedder.

Source/web/RemoteFrameClientImpl.cpp

Index: Source/web/RemoteFrameClientImpl.cpp
diff --git a/Source/web/RemoteFrameClientImpl.cpp b/Source/web/RemoteFrameClientImpl.cpp
index fa627e51b7fa805901a63cd320c18fa91c89a902..a2994e71cb2f15f2ddc09e27d439474fba297eb6 100644
--- a/Source/web/RemoteFrameClientImpl.cpp
+++ b/Source/web/RemoteFrameClientImpl.cpp
@@ -26,6 +26,11 @@ RemoteFrameClientImpl::RemoteFrameClientImpl(WebRemoteFrameImpl* webFrame)
 {
 }
 
+bool RemoteFrameClientImpl::inShadowTree() const
+{
+    return m_webFrame->inShadowTree();
+}
+
 void RemoteFrameClientImpl::willBeDetached()
 {
 }