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

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

Index: third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp b/third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp
index b664912074081ba5a020b8c0980045d2d856b970..0c868d70f6d765d9cfa035428d174c89d82a9f32 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLPreloadScanner.cpp
@@ -828,7 +828,8 @@ void TokenPreloadScanner::updatePredictedBaseURL(const Token& token) {
   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();
   }
 }