Bug 1498572 - Remove eval from harness.xul r=ckerschb

Differential Revision: https://phabricator.services.mozilla.com/D9383

--HG--
extra : moz-landing-system : lando

testing/mochitest/harness.xul

@@ -48,7 +48,7 @@ function linkAndHookup(links) {
   function populate() {
     document.getElementById("test-table").innerHTML += tableContent;
   }
-  gTestList = eval(srvScope.jsonArrayOfTestFiles(links));
+  gTestList = JSON.parse(srvScope.jsonArrayOfTestFiles(links));
   populate();
 
   hookup();