Link to PDF file (or attach file here):
[pages4.pdf](https://github.com/mozilla/pdf.js/files/1128300/pages4.pdf)

Configuration:
- Web browser and its version: Firefox 54
- Operating system and its version: Win 10
- PDF.js version: 1.8.522
- Is an extension: no

What is the expected behavior? (add screenshot)
![chrome1-1 1](https://user-images.githubusercontent.com/146436/27918380-2f74512a-6245-11e7-8525-d0038fa6c2e8.jpg)
![chrome1-2 1](https://user-images.githubusercontent.com/146436/27918425-54f8e47e-6245-11e7-9bff-127f79ad0511.jpg)


What went wrong? (add screenshot)
![screenshot from 2017-07-06 12-10-30](https://user-images.githubusercontent.com/146436/27918442-5d57624e-6245-11e7-9436-5ba31cc8bd1a.png)
![screenshot from 2017-07-06 12-10-44](https://user-images.githubusercontent.com/146436/27918454-63b486da-6245-11e7-9eb5-c03aa5c40943.png)



const drawnWidth = Math.ceil(rect[2] - rect[0]);
    const drawnHeight = Math.ceil(rect[3] - rect[1]);
    const fillCanvas = this.cachedCanvases.getCanvas(
      "fillCanvas",
      drawnWidth,
      drawnHeight,
      true
    );
    const fillCtx = fillCanvas.context;
    
    const offsetX = Math.min(cord1[0], cord2[0]);
    const offsetY = Math.min(cord1[1], cord2[1]);
    fillCtx.translate(-offsetX, -offsetY);
    fillCtx.transform.apply(fillCtx, maskToCanvas);
    
    const scaled = this._scaleImage(
      maskCanvas.canvas,
      fillCtx.mozCurrentTransformInverse
    );
    fillCtx.imageSmoothingEnabled = getImageSmoothingEnabled(
      fillCtx.mozCurrentTransform,
      img.interpolate
    );
    fillCtx.drawImage(
      scaled.img,
      0,
      0,
      scaled.img.width,
      scaled.img.height,
      0,