fix(uiGrid): Fix race condition in data watcher

modifyRows is now passed the most recent data that the dataWatchFunction has seen
Fixes race condition when retrieving templates via URL.
$q.all promise in dataWatchFunction would resolve and pass in outdated
grid data from the original dataWatchFunction call.

Fixes #4532

Author: oriondean

Diff for: src/js/core/directives/ui-grid.js

@@ -78,6 +78,8 @@
         }
       }
 
+      var mostRecentData;
+
       function dataWatchFunction(newData) {
         // gridUtil.logDebug('dataWatch fired');
         var promises = [];
@@ -90,6 +92,8 @@
           }
         }
 
+        mostRecentData = newData;
+
         if (newData) {
           // columns length is greater than the number of row header columns, which don't count because they're created automatically
           var hasColumns = self.grid.columns.length > (self.grid.rowHeaderColumns ? self.grid.rowHeaderColumns.length : 0);
@@ -118,7 +122,8 @@
           }
 
           $q.all(promises).then(function() {
-            self.grid.modifyRows(newData)
+            // use most recent data, rather than the potentially outdated data passed into watcher handler
+            self.grid.modifyRows(mostRecentData)
               .then(function () {
                 // if (self.viewport) {
                   self.grid.redrawInPlace(true);