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)

const absDet = Math.abs(m[0] * m[3] - m[2] * m[1]);
        const sqNorm1 = m[0] ** 2 + m[2] ** 2;
        const sqNorm2 = m[1] ** 2 + m[3] ** 2;
        const pixelHeight = Math.sqrt(Math.max(sqNorm1, sqNorm2)) / absDet;
        if (
          sqNorm1 !== sqNorm2 &&
          this._combinedScaleFactor * pixelHeight > 1
        ) {
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          this._cachedGetSinglePixelWidth = -(
            this._combinedScaleFactor * pixelHeight
          );
        } else if (absDet > Number.EPSILON) {
          this._cachedGetSinglePixelWidth = pixelHeight;
        } else {
           M
          this._cachedGetSinglePixelWidth = 1;
        }
      }
      return this._cachedGetSinglePixelWidth;
    }
    getCanvasPosition(x, y) {