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

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index c8a54cf0c7d3216c86bcc36a38107c160a2910d0..4b9e8ea89b04c39fbc1068608bac64bc4e75ac01 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -392,7 +392,7 @@ void FrameLoader::didBeginDocument(bool dispatch)
             headerContentLanguage.truncate(commaIndex); // kNotFound == -1 == don't truncate
             headerContentLanguage = headerContentLanguage.stripWhiteSpace(isHTMLSpace<UChar>);
             if (!headerContentLanguage.isEmpty())
-                m_frame->document()->setContentLanguage(headerContentLanguage);
+                m_frame->document()->setContentLanguage(AtomicString(headerContentLanguage));
         }
     }