Call Element::rebuildLayoutTree from Document::updateStyle directly

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp

Index: third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
diff --git a/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp b/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
index c72f2a0cdc84b8557a6fa137266e55be6b0c5142..3d9959546af7fdaf67bdc20fc745cbb0c3c36731 100644
--- a/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
+++ b/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
@@ -147,10 +147,19 @@ void ShadowRoot::recalcStyle(StyleRecalcChange change) {
 
   // There's no style to update so just calling recalcStyle means we're updated.
   clearNeedsStyleRecalc();
-  clearNeedsReattachLayoutTree();
 
   recalcDescendantStyles(change);
   clearChildNeedsStyleRecalc();
+}
+
+void ShadowRoot::rebuildLayoutTree() {
+  // ShadowRoot doesn't support custom callbacks.
+  DCHECK(!hasCustomStyleCallbacks());
+
+  StyleSharingDepthScope sharingScope(*this);
+
+  clearNeedsReattachLayoutTree();
+  rebuildChildrenLayoutTrees();
   clearChildNeedsReattachLayoutTree();
 }