[KURL] Avoid re-hashing input if is already canonicalized

third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2009 Torch Mobile, Inc. http://www.torchmobile.com/
  * Copyright (C) 2010 Google Inc. 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 810 matching lines @@
     default: { return; }
   }
 }
 
 template <typename Token>
 void TokenPreloadScanner::updatePredictedBaseURL(const Token& token) {
   ASSERT(m_predictedBaseElementURL.isEmpty());
   if (const typename Token::Attribute* hrefAttribute =
           token.getAttributeItem(hrefAttr)) {
     KURL url(m_documentURL, stripLeadingAndTrailingHTMLSpaces(
-                                hrefAttribute->value8BitIfNecessary()));
+                                hrefAttribute->value8BitIfNecessary())
+                                .isolatedCopy());
     m_predictedBaseElementURL = url.isValid() ? url.copy() : KURL();
   }
 }
 
 HTMLPreloadScanner::HTMLPreloadScanner(
     const HTMLParserOptions& options,
     const KURL& documentURL,
     std::unique_ptr<CachedDocumentParameters> documentParameters,
     const MediaValuesCached::MediaValuesCachedData& mediaValuesCachedData)
     : m_scanner(documentURL,
@@ skipping 50 matching lines @@
   defaultViewportMinWidth = document->viewportDefaultMinWidth();
   viewportMetaZeroValuesQuirk =
       document->settings() &&
       document->settings()->viewportMetaZeroValuesQuirk();
   viewportMetaEnabled =
       document->settings() && document->settings()->viewportMetaEnabled();
   referrerPolicy = document->getReferrerPolicy();
 }
 
 }  // namespace blink