Attach (recommended) or Link to PDF file here: https://www.recom-power.com/pdf/Powerline-AC-DC/RAC05-K.pdf

Configuration:
- Web browser and its version: Firefox 56.0 (64-bit)
- Operating system and its version: Windows 10 with OS Build 15063.632
- PDF.js version: ?
- Is an extension: Built-in

Steps to reproduce the problem:
1. Open Page

What is the expected behavior? To properly render the first page. 
![image](https://user-images.githubusercontent.com/1151969/31415345-b1504022-add7-11e7-855b-8030a308f7a2.png)

What went wrong? Renders poorly.
![image](https://user-images.githubusercontent.com/1151969/31415363-d8842096-add7-11e7-818d-728c1102891b.png)

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

if (this.current.resumeSMaskCtx) {
      this.resumeSMaskGroup();
    }
    
    
    if (
      this.current.activeSMask !== null &&
      (this.stateStack.length === 0 ||
        this.stateStack[this.stateStack.length - 1].activeSMask !==
          this.current.activeSMask)
    ) {
      this.endSMaskGroup();
    }
    if (this.stateStack.length !== 0) {
      this.current = this.stateStack.pop();
      this.ctx.restore();
      
      this.pendingClip = null;
      this._cachedGetSinglePixelWidth = null;
    } else {
      
      this.current.activeSMask = null;
    }
  }
  transform(a, b, c, d, e, f) {