**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):

_createMaskCanvas(img) {
    const ctx = this.ctx;
    const width = img.width,
      height = img.height;
    const fillColor = this.current.fillColor;
    const isPatternFill = this.current.patternFill;
    const maskCanvas = this.cachedCanvases.getCanvas(
      "maskCanvas",
      width,
      height
    );
    const maskCtx = maskCanvas.context;
    putBinaryImageMask(maskCtx, img);
    
    
    
    
    const objToCanvas = ctx.mozCurrentTransform;
    let maskToCanvas = Util.transform(objToCanvas, [
      1 / width,
      0,
      0,
      -1 / height,
      0,
      0,
    ]);
    maskToCanvas = Util.transform(maskToCanvas, [1, 0, 0, 1, 0, -height]);
    const cord1 = Util.applyTransform([0, 0], maskToCanvas);
    const cord2 = Util.applyTransform([width, height], maskToCanvas);
    const rect = Util.normalizeRect([cord1[0], cord1[1], cord2[0], cord2[1]]);