Swift: Clean up the test logic slightly.

Author: geoffw0

swift/ql/test/query-tests/Security/CWE-312/CleartextLoggingTest.ql

@@ -7,11 +7,10 @@ module CleartextLogging implements TestSig {
   string getARelevantTag() { result = "hasCleartextLogging" }
 
   predicate hasActualResult(Location location, string element, string tag, string value) {
-    exists(DataFlow::Node source, DataFlow::Node sink, Expr sinkExpr |
+    exists(DataFlow::Node source, DataFlow::Node sink |
       CleartextLoggingFlow::flow(source, sink) and
-      sinkExpr = sink.asExpr() and
-      location = sinkExpr.getLocation() and
-      element = sinkExpr.toString() and
+      location = sink.getLocation() and
+      element = sink.toString() and
       tag = "hasCleartextLogging" and
       value = source.asExpr().getLocation().getStartLine().toString()
     )