Link to PDF file (or attach file here):
[pages4.pdf](https://github.com/mozilla/pdf.js/files/1128300/pages4.pdf)

Configuration:
- Web browser and its version: Firefox 54
- Operating system and its version: Win 10
- PDF.js version: 1.8.522
- Is an extension: no

What is the expected behavior? (add screenshot)
![chrome1-1 1](https://user-images.githubusercontent.com/146436/27918380-2f74512a-6245-11e7-8525-d0038fa6c2e8.jpg)
![chrome1-2 1](https://user-images.githubusercontent.com/146436/27918425-54f8e47e-6245-11e7-9bff-127f79ad0511.jpg)


What went wrong? (add screenshot)
![screenshot from 2017-07-06 12-10-30](https://user-images.githubusercontent.com/146436/27918442-5d57624e-6245-11e7-9436-5ba31cc8bd1a.png)
![screenshot from 2017-07-06 12-10-44](https://user-images.githubusercontent.com/146436/27918454-63b486da-6245-11e7-9eb5-c03aa5c40943.png)



bold = "900";
    } else if (fontObj.bold) {
      bold = "bold";
    }
    const italic = fontObj.italic ? "italic" : "normal";
    const typeface = `"${name}", ${fontObj.fallbackName}`;
    
    
    
    
    let browserFontSize = size;
    if (size < MIN_FONT_SIZE) {
      browserFontSize = MIN_FONT_SIZE;
    } else if (size > MAX_FONT_SIZE) {
      browserFontSize = MAX_FONT_SIZE;
    }
    this.current.fontSizeScale = size / browserFontSize;
    this.ctx.font = `${italic} ${bold} ${browserFontSize}px ${typeface}`;
  }
  setTextRenderingMode(mode) {
    this.current.textRenderingMode = mode;
  }
  setTextRise(rise) {
    this.current.textRise = rise;
  }
  moveText(x, y) {
    this.current.x = this.current.lineX += x;
    this.current.y = this.current.lineY += y;
  }
  setLeadingMoveText(x, y) {