Read the default min-width value from the UA style sheets

Source/core/css/resolver/ViewportStyleResolver.cpp

 /*
  * Copyright (C) 2012-2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 27 matching lines @@
 #include "core/dom/Document.h"
 #include "core/dom/NodeRenderStyle.h"
 #include "core/dom/ViewportDescription.h"
 #include "core/frame/FrameView.h"
 
 namespace WebCore {
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ViewportStyleResolver);
 
 ViewportStyleResolver::ViewportStyleResolver(Document* document)
-    : m_document(document),
-    m_hasAuthorStyle(false)
+    : m_document(document)
+    , m_hasAuthorStyle(false)
 {
     ASSERT(m_document);
 }
 
 void ViewportStyleResolver::collectViewportRules(RuleSet* rules, Origin origin)
 {
     rules->compactRulesIfNeeded();
 
     const WillBeHeapVector<RawPtrWillBeMember<StyleRuleViewport> >& viewportRules = rules->viewportRules();
     for (size_t i = 0; i < viewportRules.size(); ++i)
@@ skipping 20 matching lines @@
     // respect the !important declaration (but addParsedProperty() does).
     for (unsigned i = 0; i < propertyCount; ++i)
         m_propertySet->addParsedProperty(propertySet.propertyAt(i).toCSSProperty());
 }
 
 void ViewportStyleResolver::resolve()
 {
     if (!m_document)
         return;
 
-    if (!m_propertySet || (!m_hasAuthorStyle && m_document->hasLegacyViewportTag())) {
-        ASSERT(!m_hasAuthorStyle);
-        m_propertySet = nullptr;
-        m_document->setViewportDescription(ViewportDescription());
+    if (!m_propertySet) {
+        m_document->setViewportDescription(ViewportDescription(ViewportDescription::UserAgentStyleSheet));
         return;
     }
 
     ViewportDescription description(m_hasAuthorStyle ? ViewportDescription::AuthorStyleSheet : ViewportDescription::UserAgentStyleSheet);
 
     description.userZoom = viewportArgumentValue(CSSPropertyUserZoom);
     description.zoom = viewportArgumentValue(CSSPropertyZoom);
     description.minZoom = viewportArgumentValue(CSSPropertyMinZoom);
     description.maxZoom = viewportArgumentValue(CSSPropertyMaxZoom);
     description.minWidth = viewportLengthValue(CSSPropertyMinWidth);
@@ skipping 94 matching lines @@
 
     return result;
 }
 
 void ViewportStyleResolver::trace(Visitor* visitor)
 {
     visitor->trace(m_propertySet);
 }
 
 } // namespace WebCore