IDL: For DOMString? attribute getters, use null string to represent null

Source/core/frame/NavigatorLanguage.cpp

Index: Source/core/frame/NavigatorLanguage.cpp
diff --git a/Source/core/frame/NavigatorLanguage.cpp b/Source/core/frame/NavigatorLanguage.cpp
index ad520541539e59743d64d55b07ae1a87d48346c2..8ad20438147ae81243ca6c3d69f2abfc01787318 100644
--- a/Source/core/frame/NavigatorLanguage.cpp
+++ b/Source/core/frame/NavigatorLanguage.cpp
@@ -14,9 +14,8 @@ NavigatorLanguage::NavigatorLanguage()
 {
 }
 
-AtomicString NavigatorLanguage::language(bool& isNull)
+AtomicString NavigatorLanguage::language()
 {
-    isNull = false;
     return defaultLanguage();
 }