I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

while (this.stateStack.length || this.current.activeSMask !== null) {
        this.restore();
      }
      this.ctx.restore();
      if (this.transparentCanvas) {
        this.ctx = this.compositeCtx;
        this.ctx.save();
        this.ctx.setTransform(1, 0, 0, 1, 0, 0); 
        this.ctx.drawImage(this.transparentCanvas, 0, 0);
        this.ctx.restore();
        this.transparentCanvas = null;
      }
      this.cachedCanvases.clear();
      this.webGLContext.clear();
      if (this.imageLayer) {
        this.imageLayer.endLayout();
      }
    }
    
    setLineWidth(width) {
      this.current.lineWidth = width;
      this.ctx.lineWidth = width;
    }
    setLineCap(style) {