**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):

case "BM":
          this.ctx.globalCompositeOperation = value;
          break;
        case "SMask":
          if (this.current.activeSMask) {
            
            
            
            if (
              this.stateStack.length > 0 &&
              this.stateStack[this.stateStack.length - 1].activeSMask ===
                this.current.activeSMask
            ) {
              this.suspendSMaskGroup();
            } else {
              this.endSMaskGroup();
            }
          }
          this.current.activeSMask = value ? this.tempSMask : null;
          if (this.current.activeSMask) {
            this.beginSMaskGroup();
          }
          this.tempSMask = null;
          break;
        case "TR":
          this.current.transferMaps = value;
      }
    }
  }
  beginSMaskGroup() {