Separate @viewport from other RuleSet construction.

third_party/WebKit/Source/core/dom/DocumentStyleSheetCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 11 matching lines @@
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "core/dom/DocumentStyleSheetCollection.h"
 
 #include "core/css/resolver/StyleResolver.h"
+#include "core/css/resolver/ViewportStyleResolver.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentStyleSheetCollector.h"
 #include "core/dom/ProcessingInstruction.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/StyleSheetCandidate.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
@@ skipping 81 matching lines @@
   }
   if (change.requiresFullStyleRecalc)
     document().setNeedsStyleRecalc(
         SubtreeStyleChange, StyleChangeReasonForTracing::create(
                                 StyleChangeReason::ActiveStylesheetsUpdate));
 
   collection->swap(*this);
   collection->dispose();
 }
 
+void DocumentStyleSheetCollection::updateViewport() {
+  ViewportStyleResolver& resolver =
+      document().styleEngine().ensureViewportStyleResolver();
+  resolver.reset();
+  resolver.collectViewportRulesFromUASheets();
+
+  if (RuntimeEnabledFeatures::cssViewportEnabled()) {
+    for (Node* node : m_styleSheetCandidateNodes) {
+      StyleSheetCandidate candidate(*node);
+
+      if (candidate.isImport())
+        continue;
+      StyleSheet* sheet = candidate.sheet();
+      if (!sheet)
+        continue;
+      if (!candidate.canBeActivated(
+              document().styleEngine().preferredStylesheetSetName()))
+        continue;
+      resolver.collectViewportRulesFromAuthorSheet(*toCSSStyleSheet(sheet));
+    }
+  }
+  resolver.resolve();
+}
+
 DEFINE_TRACE_WRAPPERS(DocumentStyleSheetCollection) {
   for (auto sheet : m_styleSheetsForStyleSheetList) {
     visitor->traceWrappers(sheet);
   }
 }
 }  // namespace blink