DevTools: defer styles delta calculation to until the end of the task.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index db5f3b0b2f44c73ef3afdf7fcdcee96e46f19ae8..b2e304f6171cf67a079317d0cc1399a16ea01f57 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -629,6 +629,8 @@ void Document::dispose()
 
     m_lifecycle.advanceTo(DocumentLifecycle::Disposed);
     lifecycleNotifier().notifyDocumentWasDisposed();
+
+    InspectorInstrumentation::documentDisposed(this);
 }
 
 SelectorQueryCache& Document::selectorQueryCache()