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)

this.current.strokeColor = this.getColorN_Pattern(arguments);
    }
    setFillColorN() {
      this.current.fillColor = this.getColorN_Pattern(arguments);
      this.current.patternFill = true;
    }
    setStrokeRGBColor(r, g, b) {
      const color = Util.makeHexColor(r, g, b);
      this.ctx.strokeStyle = color;
      this.current.strokeColor = color;
    }
    setFillRGBColor(r, g, b) {
      const color = Util.makeHexColor(r, g, b);
      this.ctx.fillStyle = color;
      this.current.fillColor = color;
      this.current.patternFill = false;
    }
    shadingFill(patternIR) {
      if (!this.contentVisible) {
        return;
      }
      const ctx = this.ctx;
      this.save();
      const pattern = getShadingPatternFromIR(patternIR);