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 (URL.createObjectURL && typeof Blob !== "undefined" && !forceDataSchema) {
    return URL.createObjectURL(new Blob([data], { type: contentType }));
  }
  
  const digits =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
  let buffer = `data:${contentType};base64,`;
  for (let i = 0, ii = data.length; i < ii; i += 3) {
    const b1 = data[i] & 0xff;
    const b2 = data[i + 1] & 0xff;
    const b3 = data[i + 2] & 0xff;
    const d1 = b1 >> 2,
      d2 = ((b1 & 3) << 4) | (b2 >> 4);
    const d3 = i + 1 < ii ? ((b2 & 0xf) << 2) | (b3 >> 6) : 64;
    const d4 = i + 2 < ii ? b3 & 0x3f : 64;
    buffer += digits[d1] + digits[d2] + digits[d3] + digits[d4];
  }
  return buffer;
}
export {
  AbortException,
  AnnotationActionEventType,
  AnnotationBorderStyleType,
  AnnotationFieldFlag,
  AnnotationFlag,
  AnnotationMarkedState,
  AnnotationMode,
  AnnotationReplyType,
  AnnotationReviewState,