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 (font.disableFontFace || patternFill) {
        ctx.save();
        ctx.translate(x, y);
        ctx.beginPath();
        addToPath(ctx, fontSize);
        if (patternTransform) {
          ctx.setTransform.apply(ctx, patternTransform);
        }
        if (
          fillStrokeMode === TextRenderingMode.FILL ||
          fillStrokeMode === TextRenderingMode.FILL_STROKE
        ) {
          ctx.fill();
        }
        if (
          fillStrokeMode === TextRenderingMode.STROKE ||
          fillStrokeMode === TextRenderingMode.FILL_STROKE
        ) {
          if (resetLineWidthToOne) {
            ctx.resetTransform();
            ctx.lineWidth = Math.round(this._combinedScaleFactor);
          }
          ctx.stroke();
        }
        ctx.restore();
      } else {
        if (
          fillStrokeMode === TextRenderingMode.FILL ||
          fillStrokeMode === TextRenderingMode.FILL_STROKE
        ) {