[import] The first <link rel=import> should win in the cascading order computation.

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)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 63 matching lines @@
                 return;
             }
 
             continue;
         }
 
         if (candidate.isImport()) {
             Document* document = candidate.importedDocument();
             if (!document)
                 continue;
+            if (collector.hasVisited(document))
+                continue;
+            collector.willVisit(document);
             document->styleEngine()->updateStyleSheetsInImport(collector);
             continue;
         }
 
         if (candidate.isEnabledAndLoading()) {
             // it is loading but we should still decide which style sheet set to use
             if (candidate.hasPreferrableName(engine->preferredStylesheetSetName()))
                 engine->selectStylesheetSetName(candidate.title());
             continue;
         }
@@ skipping 49 matching lines @@
     m_scopingNodesForStyleScoped.didRemoveScopingNodes();
 
     collection.swap(*this);
 
     updateUsesRemUnits();
 
     return change.requiresFullStyleRecalc;
 }
 
 }