Pass exception stack from AutoJSAPI::ReportException.

Differential Revision: https://phabricator.services.mozilla.com/D67791

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1623226
gecko-commit: 312da02ea6d6aef4ae98390fd2939543c3cd6b64
gecko-integration-branch: autoland
gecko-reviewers: baku

html/webappapis/scripting/processing-model-2/window-onerror-runtime-error-throw.html

@@ -20,6 +20,10 @@
     var error_count = 0;
     window.onerror = function(msg, url, lineno) {
       ++error_count;
+      test(function() {assert_equals(url, window.location.href)},
+           "correct url passed to window.onerror");
+      test(function() {assert_equals(lineno, 36)},
+           "correct line number passed to window.onerror");
     };
   </script>
   <script>