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)

if (
      !Number.isInteger(pageNumber) ||
      pageNumber <= 0 ||
      pageNumber > this._numPages
    ) {
      return Promise.reject(new Error("Invalid page request"));
    }
    const pageIndex = pageNumber - 1;
    if (pageIndex in this.pagePromises) {
      return this.pagePromises[pageIndex];
    }
    const promise = this.messageHandler
      .sendWithPromise("GetPage", {
        pageIndex,
      })
      .then(pageInfo => {
        if (this.destroyed) {
          throw new Error("Transport destroyed");
        }
        const page = new PDFPageProxy(
          pageIndex,
          pageInfo,
          this,
          this._params.ownerDocument,
          this._params.pdfBug
        );
        this.pageCache[pageIndex] = page;
        return page;
      });