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)



const glyph = glyphs[i];
      if (isNum(glyph)) {
        x += (spacingDir * glyph * fontSize) / 1000;
        continue;
      }
      let restoreNeeded = false;
      const spacing = (glyph.isSpace ? wordSpacing : 0) + charSpacing;
      const character = glyph.fontChar;
      const accent = glyph.accent;
      let scaledX, scaledY;
      let width = glyph.width;
      if (vertical) {
        const vmetric = glyph.vmetric || defaultVMetrics;
        const vx =
          -(glyph.vmetric ? vmetric[1] : width * 0.5) * widthAdvanceScale;
        const vy = vmetric[2] * widthAdvanceScale;
        width = vmetric ? -vmetric[0] : width;
        scaledX = vx / fontSizeScale;
        scaledY = (x + vy) / fontSizeScale;
      } else {
        scaledX = x / fontSizeScale;
        scaledY = 0;
      }
      if (font.remeasure && width > 0) {
        
        
        
        const measuredWidth =
          ((ctx.measureText(character).width * 1000) / fontSize) *
          fontSizeScale;