Prevent uiGrid styles breaking, columns collapsing

Prevent uiGrid styles breaking(columns collapsing) for those cases when some uiGrids are invisible on page (in some hidden dialogs or tabs).
We don't need to do gridResize() when grid is not visible.

Author: Nickproger

packages/core/src/js/directives/ui-grid.js

@@ -338,6 +338,9 @@ function uiGridDirective($window, gridUtil, uiGridConstants) {
 
           // Resize the grid on window resize events
           function gridResize() {
+            if (!$elm.is(':visible')) {
+              return;
+            }
             grid.gridWidth = $scope.gridWidth = gridUtil.elementWidth($elm);
             grid.gridHeight = $scope.gridHeight = gridUtil.elementHeight($elm);