Always use getAABB for bitmap skins when determining fenced position

src/BitmapSkin.js

@@ -59,6 +59,15 @@ class BitmapSkin extends Skin {
         return this._texture;
     }
 
+    /**
+     * Get the bounds of the drawable for determining its fenced position.
+     * @param {Array<number>} drawable - The Drawable instance this skin is using.
+     * @return {!Rectangle} The drawable's bounds. For compatibility with Scratch 2, we always use getAABB for bitmaps.
+     */
+    getFenceBounds (drawable) {
+        return drawable.getAABB();
+    }
+
     /**
      * Set the contents of this skin to a snapshot of the provided bitmap data.
      * @param {ImageData|HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} bitmapData - new contents for this skin.

src/RenderWebGL.js

@@ -1316,7 +1316,7 @@ class RenderWebGL extends EventEmitter {
 
         const dx = x - drawable._position[0];
         const dy = y - drawable._position[1];
-        const aabb = drawable.getFastBounds();
+        const aabb = drawable._skin.getFenceBounds(drawable);
         const inset = Math.floor(Math.min(aabb.width, aabb.height) / 2);
 
         const sx = this._xRight - Math.min(FENCE_WIDTH, inset);

src/Skin.js

@@ -136,6 +136,15 @@ class Skin extends EventEmitter {
         return null;
     }
 
+    /**
+     * Get the bounds of the drawable for determining its fenced position.
+     * @param {Array<number>} drawable - The Drawable instance this skin is using.
+     * @return {!Rectangle} The drawable's bounds.
+     */
+    getFenceBounds (drawable) {
+        return drawable.getFastBounds();
+    }
+
     /**
      * Update and returns the uniforms for this skin.
      * @param {Array<number>} scale - The scaling factors to be used.