Implement updateViaCache flag and no-cache by default for main service worker scripts

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 78 matching lines @@
                         UseCounter::HTMLLinkElementReferrerPolicyAttribute);
     }
   } else if (name == sizesAttr) {
     m_sizes->setValue(value);
   } else if (name == mediaAttr) {
     m_media = value.lower();
     process();
   } else if (name == scopeAttr) {
     m_scope = value;
     process();
+  } else if (name == usecacheAttr) {
+    m_useCache = !value.isNull();
+    process();
   } else if (name == disabledAttr) {
     UseCounter::count(document(), UseCounter::HTMLLinkElementDisabled);
     if (LinkStyle* link = linkStyle())
       link->setDisabledState(!value.isNull());
   } else {
     if (name == titleAttr) {
       if (LinkStyle* link = linkStyle())
         link->setSheetTitle(value);
     }
 
@@ skipping 261 matching lines @@
   LinkLoaderClient::trace(visitor);
   DOMTokenListObserver::trace(visitor);
 }
 
 DEFINE_TRACE_WRAPPERS(HTMLLinkElement) {
   visitor->traceWrappers(m_relList);
   HTMLElement::traceWrappers(visitor);
 }
 
 }  // namespace blink