**Link to PDF file (or attach file here):**
[tocheckFile.pdf](https://github.com/mozilla/pdf.js/files/240714/tocheckFile.pdf)

**Configuration:**
- Web browser and its version: FF45.0.2, Chrome Version 50.0.2661.86 (64-bit) 
- Operating system and its version: Mac OSX El Capitan

**\- PDF.js version:**
PDFJS.version = '1.1.215';
PDFJS.build = 'c9a7498';

**Steps to reproduce the problem:**
1. Use the lib to generate a PDF preview.

**What is the expected behavior? (add screenshot)**
PDF preview should have rendered completely. (frog head should be complete)

**What went wrong? (add screenshot)**
<img width="952" alt="imagesnotrenderinginpreview" src="https://cloud.githubusercontent.com/assets/10231850/14889265/cecb2d64-0d66-11e6-98e1-da2d39728552.png">

See attached screenshot in regards to the pdf file

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

const { context: ctx } = this.cachedCanvases.getCanvas(
      "isFontSubpixelAAEnabled",
      10,
      10
    );
    ctx.scale(1.5, 1);
    ctx.fillText("I", 0, 10);
    const data = ctx.getImageData(0, 0, 10, 10).data;
    let enabled = false;
    for (let i = 3; i < data.length; i += 4) {
      if (data[i] > 0 && data[i] < 255) {
        enabled = true;
        break;
      }
    }
    return shadow(this, "isFontSubpixelAAEnabled", enabled);
  }
  showText(glyphs) {