Change DrawSprite calls to provide scales instead of sizes.

This allows us to remove a hacky workaround for calculating
depth offsets when sprites have size.Z == 0.

OpenRA.Mods.Common/Widgets/SpriteWidget.cs

@@ -77,9 +77,8 @@ namespace OpenRA.Mods.Common.Widgets
 				cachedScale = scale;
 			}
 
-			var size = new float2(sprite.Size.X * scale, sprite.Size.Y * scale);
 			Game.Renderer.EnableAntialiasingFilter();
-			Game.Renderer.SpriteRenderer.DrawSprite(sprite, RenderOrigin + offset, pr, size);
+			Game.Renderer.SpriteRenderer.DrawSprite(sprite, pr, RenderOrigin + offset, scale);
 			Game.Renderer.DisableAntialiasingFilter();
 		}
 	}