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 (!this.contentVisible) {
        return;
      }
      const width = imgData.width;
      const height = imgData.height;
      const ctx = this.ctx;
      this.save();
      
      ctx.scale(1 / width, -1 / height);
      const currentTransform = ctx.mozCurrentTransformInverse;
      let widthScale = Math.max(
        Math.hypot(currentTransform[0], currentTransform[1]),
        1
      );
      let heightScale = Math.max(
        Math.hypot(currentTransform[2], currentTransform[3]),
        1
      );
      let imgToPaint, tmpCanvas, tmpCtx;
      
      if (
        (typeof HTMLElement === "function" && imgData instanceof HTMLElement) ||
        !imgData.data
      ) {
        imgToPaint = imgData;
      } else {
        tmpCanvas = this.cachedCanvases.getCanvas("inlineImage", width, height);