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!
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      const m = this.ctx.mozCurrentTransform;
      const absDet = Math.abs(m[0] * m[3] - m[2] * m[1]);
      const sqNorm1 = m[0] ** 2 + m[2] ** 2;
      const sqNorm2 = m[1] ** 2 + m[3] ** 2;
      const pixelHeight = Math.sqrt(Math.max(sqNorm1, sqNorm2)) / absDet;
      if (sqNorm1 !== sqNorm2 && this._combinedScaleFactor * pixelHeight > 1) {
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        this._cachedGetSinglePixelWidth = -(
          this._combinedScaleFactor * pixelHeight
        );
      } else if (absDet > Number.EPSILON) {
        this._cachedGetSinglePixelWidth = pixelHeight;
      } else {
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        this._cachedGetSinglePixelWidth = 1;
      }
    }
    return this._cachedGetSinglePixelWidth;
  }
  getCanvasPosition(x, y) {