Minor improvement to flow analysis as requested by @kevinvandervlist

This is just a trivial fix for the specific case of a while with the
constant `true` as condition. A complete solution would require flow
analysis and constant propagation in the type checker.

We may explore this in the future.

src/org/rascalmpl/core/library/lang/rascalcore/check/PathAnalysis.rsc

@@ -38,8 +38,8 @@ bool returnsViaAllPath((Statement) `try <Statement body> <Catch+ handlers> final
     
 
 bool returnsViaAllPath((Statement) `<Label label> while( <{Expression ","}+ conditions> ) <Statement body>`, str fname,  Collector c){
-    returnsViaAllPath(body, fname, c); 
-    return false;
+    br = returnsViaAllPath(body, fname, c); 
+    return ("<conditions>" == "true") ? br : false;
 }
 
 bool returnsViaAllPath((Statement) `<Label label> do <Statement body> while ( <Expression condition> ) ;`, str fname,  Collector c){