Fix undefined variables x0, x1, y0, y1 in paintFormXObjectBegin

Use bounds array indices instead of the undefined variables when
calling recordClipBox. bounds is [minX, minY, maxX, maxY] from
Util.intersect, and recordClipBox expects (minX, maxX, minY, maxY).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: pengkunbin

src/display/canvas.js

@@ -2565,7 +2565,14 @@ class CanvasGraphics {
       bounds = Util.intersect(bounds, canvasBounds) || canvasBounds;
       const clip = buildClipFromDeviceBounds(bounds, this.baseTransform);
       this.ctx.clip(clip);
-      this.dependencyTracker?.recordClipBox(opIdx, this.ctx, x0, x1, y0, y1);
+      this.dependencyTracker?.recordClipBox(
+        opIdx,
+        this.ctx,
+        bounds[0],
+        bounds[2],
+        bounds[1],
+        bounds[3]
+      );
       this.endPath(opIdx);
     }
   }