Content changes for grid splitting (#7645)

Co-authored-by: Vera Aguilera Puerto <gradientvera@outlook.com>

Content.IntegrationTests/Tests/EntityTest.cs

@@ -9,6 +9,7 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
+using Robust.Shared.Maths;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Timing;
 
@@ -249,10 +250,8 @@ namespace Content.IntegrationTests.Tests
 
                 var tileDefinition = tileDefinitionManager["underplating"];
                 var tile = new Tile(tileDefinition.TileId);
-                var coordinates = grid.ToCoordinates();
-
-                grid.SetTile(coordinates, tile);
 
+                grid.SetTile(Vector2i.Zero, tile);
                 mapManager.DoMapInitialize(mapId);
             });