Link to PDF file (or attach file here):
[RP_25884_V2_UEL Semi Finals 2016-17_concepts.pdf](https://github.com/mozilla/pdf.js/files/994423/RP_25884_V2_UEL.Semi.Finals.2016-17_concepts.pdf)

Configuration:
- Web browser and its version: Chrome 58, Firefox 53
- Operating system and its version: MacOS 10.11.6
- PDF.js version:
- Is an extension: No

Steps to reproduce the problem:
1.  View the file the file


What is the expected behavior? (add screenshot)
<img width="560" alt="screen shot 2017-05-11 at 2 06 36 pm" src="https://cloud.githubusercontent.com/assets/2474027/25971992/189f4ebe-3653-11e7-8847-c9011984cb8d.png">

What went wrong? (add screenshot)
Textlayer exists here but font fails to render. No warning in the console from what I can see. Maybe related to the gradient?

<img width="637" alt="screen shot 2017-05-11 at 2 06 20 pm" src="https://cloud.githubusercontent.com/assets/2474027/25971997/1b518cc6-3653-11e7-96c0-9a03ffcb7d6e.png">

Thanks!
if (hasBackdrop) {
      composeSMaskBackdrop(maskData.data, r0, g0, b0);
    }
    composeFn(maskData.data, layerData.data, transferMap);
    maskCtx.putImageData(layerData, 0, row);
  }
}
function composeSMask(ctx, smask, layerCtx) {
  const mask = smask.canvas;
  const maskCtx = smask.context;
  ctx.setTransform(
    smask.scaleX,
    0,
    0,
    smask.scaleY,
    smask.offsetX,
    smask.offsetY
  );
  genericComposeSMask(
    maskCtx,
    layerCtx,
    mask.width,
    mask.height,
    smask.subtype,
    smask.backdrop,
    smask.transferMap
  );
  ctx.drawImage(mask, 0, 0);
}
function getImageSmoothingEnabled(transform, interpolate) {