Remove unused Gulp target for testing

To run the regression tests, developers use `gulp browsertest` and the
bot uses `gulp bottest`. We're not passing the `noreftest` option
anywhere in the code (probably because the `bottest` command takes care
of this already), so we should remove this.

gulpfile.js

@@ -1044,10 +1044,6 @@ gulp.task('browsertest', function () {
   return createTestSource('browser');
 });
 
-gulp.task('browsertest-noreftest', function () {
-  return createTestSource('browser (no reftest)');
-});
-
 gulp.task('unittest', function () {
   return createTestSource('unit');
 });

make.js

@@ -186,11 +186,7 @@ target.bottest = function() {
 // make browsertest
 //
 target.browsertest = function(options) {
-  if (options && options.noreftest) {
-    execGulp('browsertest-noreftest');
-  } else {
-    execGulp('browsertest');
-  }
+  execGulp('browsertest');
 };
 
 //