reject hover promise if didn't resolve after 100ms

Author: etpinard

test/jasmine/tests/transform_sort_test.js

@@ -273,14 +273,18 @@ describe('Test sort transform interactions:', function() {
         }
 
         function hover(gd, id) {
-            return new Promise(function(resolve) {
+            return new Promise(function(resolve, reject) {
                 gd.once('plotly_hover', function(eventData) {
                     delete gd._lastHoverTime;
                     resolve(eventData);
                 });
 
                 var pos = getPxPos(gd, id);
                 mouseEvent('mousemove', pos[0], pos[1]);
+
+                setTimeout(function() {
+                    reject('plotly_hover did not get called!');
+                }, 100);
             });
         }