Use Math.ceil and Math.floor to match Scratch 2 logic

src/RenderWebGL.js

@@ -1316,21 +1316,20 @@ class RenderWebGL extends EventEmitter {
 
         const dx = x - drawable._position[0];
         const dy = y - drawable._position[1];
-
         const aabb = drawable.getFastBounds();
         const inset = Math.floor(Math.min(aabb.width, aabb.height) / 2);
 
         const sx = this._xRight - Math.min(FENCE_WIDTH, inset);
         if (aabb.right + dx < -sx) {
-            x = drawable._position[0] - (sx + aabb.right);
+            x = Math.ceil(drawable._position[0] - (sx + aabb.right));
         } else if (aabb.left + dx > sx) {
-            x = drawable._position[0] + (sx - aabb.left);
+            x = Math.floor(drawable._position[0] + (sx - aabb.left));
         }
         const sy = this._yTop - Math.min(FENCE_WIDTH, inset);
         if (aabb.top + dy < -sy) {
-            y = drawable._position[1] - (sy + aabb.top);
+            y = Math.ceil(drawable._position[1] - (sy + aabb.top));
         } else if (aabb.bottom + dy > sy) {
-            y = drawable._position[1] + (sy - aabb.bottom);
+            y = Math.floor(drawable._position[1] + (sy - aabb.bottom));
         }
         return [x, y];
     }