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

Source/core/html/track/vtt/VTTParser.cpp

Index: Source/core/html/track/vtt/VTTParser.cpp
diff --git a/Source/core/html/track/vtt/VTTParser.cpp b/Source/core/html/track/vtt/VTTParser.cpp
index e1b4b2a372d7c8f9c987fb97876c22a9bb280ebe..4dbf0402bc9e2395749bc861f85206f55804e496 100644
--- a/Source/core/html/track/vtt/VTTParser.cpp
+++ b/Source/core/html/track/vtt/VTTParser.cpp
@@ -301,7 +301,7 @@ VTTParser::ParseState VTTParser::collectCueId(const String& line)
 {
     if (line.contains("-->"))
         return collectTimingsAndSettings(line);
-    m_currentId = line;
+    m_currentId = AtomicString(line);
     return TimingsAndSettings;
 }
 
@@ -439,7 +439,7 @@ void VTTParser::createNewCue()
 
 void VTTParser::resetCueValues()
 {
-    m_currentId = emptyString();
+    m_currentId = emptyAtom;
     m_currentSettings = emptyString();
     m_currentStartTime = 0;
     m_currentEndTime = 0;