qmljs: do not show warnings for not fully supported languages

Change-Id: Ie153caefcbb0f5d6d627697fd324d0cd0e3fa31f
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/libs/qmljs/qmljsdocument.h

@@ -65,6 +65,7 @@ public:
     };
 
     static bool isQmlLikeLanguage(Language languge);
+    static bool isFullySupportedLanguage(Language language);
 protected:
     Document(const QString &fileName, Language language);