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)

this.ctx.lineCap = LINE_CAP_STYLES[style];
    }
    setLineJoin(style) {
      this.ctx.lineJoin = LINE_JOIN_STYLES[style];
    }
    setMiterLimit(limit) {
      this.ctx.miterLimit = limit;
    }
    setDash(dashArray, dashPhase) {
      const ctx = this.ctx;
      if (ctx.setLineDash !== undefined) {
        ctx.setLineDash(dashArray);
        ctx.lineDashOffset = dashPhase;
      }
    }
    setRenderingIntent(intent) {
      
    }
    setFlatness(flatness) {
      
    }
    setGState(states) {
      for (let i = 0, ii = states.length; i < ii; i++) {
        const state = states[i];
        const key = state[0];
        const value = state[1];
        switch (key) {
          case "LW":