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._messageHandler = messageHandler;
              this._port = worker;
              this._webWorker = worker;
              if (!data.supportTransfers) {
                this.postMessageTransfers = false;
              }
              this._readyCapability.resolve();
              
              messageHandler.send("configure", {
                verbosity: this.verbosity,
              });
            } else {
              this._setupFakeWorker();
              messageHandler.destroy();
              worker.terminate();
            }
          });
          messageHandler.on("ready", data => {
            worker.removeEventListener("error", onWorkerError);
            if (this.destroyed) {
              terminateEarly();
              return; 
            }
            try {
              sendTest();
            } catch (e) {
              
              this._setupFakeWorker();
            }