Separate @viewport from other RuleSet construction.

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 413 matching lines @@
     // TODO(majidvp): It seems that this only needs to be called when size
     // is updated ignoring any change in the location.
     if (layoutView.usesCompositing())
       layoutView.compositor()->frameViewDidChangeSize();
   }
 
   if (frameSizeChanged) {
     viewportSizeChanged(newRect.width() != oldRect.width(),
                         newRect.height() != oldRect.height());
 
-    if (m_frame->isMainFrame())
+    if (m_frame->isMainFrame()) {
       m_frame->host()->visualViewport().mainFrameDidChangeSize();
+      if (Document* document = m_frame->document())
+        document->styleEngine().initialViewportChanged();
+    }
     frame().loader().restoreScrollPositionAndViewState();
   }
 }
 
 Page* FrameView::page() const {
   return frame().page();
 }
 
 LayoutView* FrameView::layoutView() const {
   return frame().contentLayoutObject();
@@ skipping 4027 matching lines @@
 }
 
 bool FrameView::canThrottleRendering() const {
   if (!RuntimeEnabledFeatures::renderingPipelineThrottlingEnabled())
     return false;
   return m_subtreeThrottled ||
          (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 }  // namespace blink