Attach (recommended) or Link to PDF file here: https://www.recom-power.com/pdf/Powerline-AC-DC/RAC05-K.pdf

Configuration:
- Web browser and its version: Firefox 56.0 (64-bit)
- Operating system and its version: Windows 10 with OS Build 15063.632
- PDF.js version: ?
- Is an extension: Built-in

Steps to reproduce the problem:
1. Open Page

What is the expected behavior? To properly render the first page. 
![image](https://user-images.githubusercontent.com/1151969/31415345-b1504022-add7-11e7-855b-8030a308f7a2.png)

What went wrong? Renders poorly.
![image](https://user-images.githubusercontent.com/1151969/31415363-d8842096-add7-11e7-818d-728c1102891b.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension): ?

if (font.disableFontFace || patternFill) {
      ctx.save();
      ctx.translate(x, y);
      ctx.beginPath();
      addToPath(ctx, fontSize);
      if (patternTransform) {
        ctx.setTransform.apply(ctx, patternTransform);
      }
      if (
        fillStrokeMode === TextRenderingMode.FILL ||
        fillStrokeMode === TextRenderingMode.FILL_STROKE
      ) {
        ctx.fill();
      }
      if (
        fillStrokeMode === TextRenderingMode.STROKE ||
        fillStrokeMode === TextRenderingMode.FILL_STROKE
      ) {
        if (resetLineWidthToOne) {
          ctx.resetTransform();
          ctx.lineWidth = Math.round(this._combinedScaleFactor);
        }
        ctx.stroke();
      }
      ctx.restore();
    } else {
      if (
        fillStrokeMode === TextRenderingMode.FILL ||
        fillStrokeMode === TextRenderingMode.FILL_STROKE
      ) {