QmlJS checks: Don't complain about alias properties.

Change-Id: I6721b42a6ae8cc4de3d85754bf12c95f7366212e
Reviewed-on: http://codereview.qt-project.org/4395
Reviewed-by: Christian Kamm <christian.d.kamm@nokia.com>

src/libs/qmljs/qmljscheck.cpp

@@ -117,6 +117,7 @@ public:
         validBuiltinPropertyNames.insert(QLatin1String("url"));
         validBuiltinPropertyNames.insert(QLatin1String("variant"));
         validBuiltinPropertyNames.insert(QLatin1String("vector3d"));
+        validBuiltinPropertyNames.insert(QLatin1String("alias"));
     }
 
     QSet<QString> validBuiltinPropertyNames;