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)

ctx.fillStyle = pattern.getPattern(ctx, this, true);
      const inv = ctx.mozCurrentTransformInverse;
      if (inv) {
        const canvas = ctx.canvas;
        const width = canvas.width;
        const height = canvas.height;
        const bl = Util.applyTransform([0, 0], inv);
        const br = Util.applyTransform([0, height], inv);
        const ul = Util.applyTransform([width, 0], inv);
        const ur = Util.applyTransform([width, height], inv);
        const x0 = Math.min(bl[0], br[0], ul[0], ur[0]);
        const y0 = Math.min(bl[1], br[1], ul[1], ur[1]);
        const x1 = Math.max(bl[0], br[0], ul[0], ur[0]);
        const y1 = Math.max(bl[1], br[1], ul[1], ur[1]);
        this.ctx.fillRect(x0, y0, x1 - x0, y1 - y0);
      } else {
        
        
        
        
        
        this.ctx.fillRect(-1e10, -1e10, 2e10, 2e10);
      }
      this.restore();
    }
    
    beginInlineImage() {
      unreachable("Should not call beginInlineImage");
    }
    beginImageData() {