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 d83f657479a485ca74ebbbeae690c675c3dcf2c0..e50b914e789276241ef4e261d75216217f9904bb 100644
--- a/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
+++ b/third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp
@@ -134,6 +134,16 @@ void ShadowRoot::recalcStyle(StyleRecalcChange change) {
 
   recalcDescendantStyles(change);
   clearChildNeedsStyleRecalc();
+}
+
+void ShadowRoot::rebuildLayoutTree() {
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
+  // ShadowRoot doesn't support custom callbacks.
+  DCHECK(!hasCustomStyleCallbacks());
+  clearNeedsReattachLayoutTree();
+  rebuildDescendantLayoutTree();
   clearChildNeedsReattachLayoutTree();
 }