fix: 🐛 ensure viewport height cannot be negative

Closes: #3034

Author: marcelo-portugal

packages/cellnav/test/uiGridCellNavService.spec.js

@@ -201,7 +201,7 @@ describe('ui.grid.edit uiGridCellNavService', function() {
 			$timeout.flush();
 
 			expect(args.grid).toEqual(grid);
-			expect(Math.round(args.y.percentage * 10) / 10).toBe(0.4);
+			expect(Math.round(args.y.percentage * 10) / 10).toBe(0.5);
 			expect(isNaN(args.x.percentage)).toEqual(true);
 		});
 
@@ -233,7 +233,7 @@ describe('ui.grid.edit uiGridCellNavService', function() {
 			});
 			$timeout.flush();
 
-			expect(Math.round(args.y.percentage * 10) / 10).toEqual(0.5);
+			expect(Math.round(args.y.percentage * 10) / 10).toEqual(0.6);
 			expect(args.x).toBe(null);
 		});
 

packages/core/src/js/factories/Grid.js

@@ -1685,7 +1685,7 @@ angular.module('ui.grid')
 
     // gridUtil.logDebug('viewPortHeight', viewPortHeight);
 
-    return viewPortHeight;
+    return viewPortHeight > 0 ? viewPortHeight : 0;
   };
 
   Grid.prototype.getViewportWidth = function getViewportWidth() {

packages/core/src/js/factories/GridRenderContainer.js

@@ -229,7 +229,7 @@ angular.module('ui.grid')
 
     viewPortHeight = viewPortHeight + adjustment.height;
 
-    return viewPortHeight;
+    return viewPortHeight > 0 ? viewPortHeight : 0;
   };
 
   GridRenderContainer.prototype.getViewportWidth = function getViewportWidth() {