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)

cancel() {},
      };
    }
    let cancelled = false;
    const ensureNotCancelled = () => {
      if (cancelled) {
        throw new RenderingCancelledException(
          `Rendering cancelled, page ${this.id}`,
          "svg"
        );
      }
    };
    const pdfPage = this.pdfPage;
    const actualSizeViewport = this.viewport.clone({ scale: CSS_UNITS });
    const promise = pdfPage.getOperatorList().then(opList => {
      ensureNotCancelled();
      const svgGfx = new SVGGraphics(
        pdfPage.commonObjs,
        pdfPage.objs,
         viewerCompatibilityParams.disableCreateObjectURL
      );
      return svgGfx.getSVG(opList, actualSizeViewport).then(svg => {
        ensureNotCancelled();
        this.svg = svg;
        this.paintedViewportMap.set(svg, actualSizeViewport);