Attach (recommended) or Link to PDF file here:
[Test file.pdf](https://github.com/mozilla/pdf.js/files/4656226/Test.file.pdf)

Configuration:
- Web browser and its version: Chrome Version 81.0.4044.138 (Official Build) (64-bit)
- Operating system and its version: Windows 10
- PDF.js version: latest
- Is a browser extension: no

Steps to reproduce the problem:
1. Open [https://mozilla.github.io/pdf.js/web/viewer.html](https://mozilla.github.io/pdf.js/web/viewer.html)
2. Load the provided .pdf file

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5569382/82438616-02c3fe80-9aa2-11ea-9003-b75ea1e7aac6.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5569382/82438640-09527600-9aa2-11ea-810b-071da7e37896.png)


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: function CanvasGraphics_beginSMaskGroup() {
      const activeSMask = this.current.activeSMask;
      const drawnWidth = activeSMask.canvas.width;
      const drawnHeight = activeSMask.canvas.height;
      const cacheId = "smaskGroupAt" + this.groupLevel;
      const scratchCanvas = this.cachedCanvases.getCanvas(
        cacheId,
        drawnWidth,
        drawnHeight,
        true