Introduce setNeedsActiveStyleUpdate for adding/removing stylesheets.

third_party/WebKit/Source/core/html/HTMLStyleElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLStyleElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLStyleElement.cpp b/third_party/WebKit/Source/core/html/HTMLStyleElement.cpp
index a728781ed09cc0f7751c422b273c664fa8526c27..d17c0e07ed1b9d0da1db1b78bf6cb94e02436e07 100644
--- a/third_party/WebKit/Source/core/html/HTMLStyleElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLStyleElement.cpp
@@ -26,6 +26,7 @@
 #include "core/HTMLNames.h"
 #include "core/css/MediaList.h"
 #include "core/dom/Document.h"
+#include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/events/EventSender.h"
@@ -68,7 +69,7 @@ void HTMLStyleElement::parseAttribute(const QualifiedName& name, const AtomicStr
         m_sheet->setTitle(value);
     } else if (name == mediaAttr && inDocument() && document().isActive() && m_sheet) {
         m_sheet->setMediaQueries(MediaQuerySet::create(value));
-        document().modifiedStyleSheet(m_sheet.get());
+        document().styleEngine().setNeedsActiveStyleUpdate(m_sheet.get(), FullStyleUpdate);
     } else {
         HTMLElement::parseAttribute(name, oldValue, value);
     }