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)

let pattern;
      if (IR[0] === "TilingPattern") {
        const color = IR[1];
        const baseTransform =
          this.baseTransform || this.ctx.mozCurrentTransform.slice();
        const canvasGraphicsFactory = {
          createCanvasGraphics: ctx => {
            return new CanvasGraphics(
              ctx,
              this.commonObjs,
              this.objs,
              this.canvasFactory,
              this.webGLContext
            );
          },
        };
        pattern = new TilingPattern(
          IR,
          color,
          this.ctx,
          canvasGraphicsFactory,
          baseTransform
        );
      } else {
        pattern = getShadingPatternFromIR(IR);
      }
      return pattern;
    }
    setStrokeColorN() {