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!
for (j = 0; j < thisChunkHeight; j++) {
        const srcDiff = srcLength - srcPos;
        let k = 0;
        const kEnd = srcDiff > fullSrcDiff ? width : srcDiff * 8 - 7;
        const kEndUnrolled = kEnd & ~7;
        let mask = 0;
        let srcByte = 0;
        for (; k < kEndUnrolled; k += 8) {
          srcByte = src[srcPos++];
          dest32[destPos++] = srcByte & 128 ? white : black;
          dest32[destPos++] = srcByte & 64 ? white : black;
          dest32[destPos++] = srcByte & 32 ? white : black;
          dest32[destPos++] = srcByte & 16 ? white : black;
          dest32[destPos++] = srcByte & 8 ? white : black;
          dest32[destPos++] = srcByte & 4 ? white : black;
          dest32[destPos++] = srcByte & 2 ? white : black;
          dest32[destPos++] = srcByte & 1 ? white : black;
        }
        for (; k < kEnd; k++) {
          if (mask === 0) {
            srcByte = src[srcPos++];
            mask = 128;
          }
          dest32[destPos++] = srcByte & mask ? white : black;
          mask >>= 1;
        }
      }
      
      while (destPos < dest32DataLength) {
        dest32[destPos++] = 0;