Make calls to AtomicString(const String&) explicit in page/

Source/core/page/PageSerializer.cpp

Index: Source/core/page/PageSerializer.cpp
diff --git a/Source/core/page/PageSerializer.cpp b/Source/core/page/PageSerializer.cpp
index 401bcbd51b9660f23c64c7a03209ab948fa6b4e1..033f8c592242092ab4025a892c7296d51e664b8c 100644
--- a/Source/core/page/PageSerializer.cpp
+++ b/Source/core/page/PageSerializer.cpp
@@ -163,7 +163,7 @@ void SerializerMarkupAccumulator::appendCustomAttributes(StringBuilder& out, Ele
 
     // We need to give a fake location to blank frames so they can be referenced by the serialized frame.
     url = m_serializer->urlForBlankFrame(frame);
-    appendAttribute(out, element, Attribute(frameOwnerURLAttributeName(*frameOwner), url.string()), namespaces);
+    appendAttribute(out, element, Attribute(frameOwnerURLAttributeName(*frameOwner), AtomicString(url.string())), namespaces);
 }
 
 void SerializerMarkupAccumulator::appendEndTag(Node* node)