qmljs: add check for comparisons not depending on values

currently we mainly try to warn about primitive == null/undefined or
primitive === non primitive.
There are other that we could warn about null==null null==undefined,
but I feel that they might be triggered too much by clean code.

Change-Id: Id43d838d60a4e13f361be34e4bb38211777a081e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/libs/qmljs/qmljsstaticanalysismessage.cpp

@@ -247,6 +247,8 @@ StaticAnalysisMessages::StaticAnalysisMessages()
            tr("Hit maximum recursion limit when visiting AST."));
     newMsg(ErrTypeIsInstantiatedRecursively, Error,
             tr("Type cannot be instantiated recursively (%1)."), 1);
+    newMsg(WarnLogicalValueDoesNotDependOnValues, Warning,
+           tr("Logical value does not depend on actual values"));
 }
 
 } // anonymous namespace