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)

loadingTask.onProgress({
                loaded: evt.loaded,
                total: evt.total,
              });
            }
          };
        }
        headersCapability.resolve({
          isStreamingSupported: fullReader.isStreamingSupported,
          isRangeSupported: fullReader.isRangeSupported,
          contentLength: fullReader.contentLength,
        });
      }, headersCapability.reject);
      return headersCapability.promise;
    });
    messageHandler.on("GetRangeReader", (data, sink) => {
      assert(
        this._networkStream,
        "GetRangeReader - no `IPDFStream` instance available."
      );
      const rangeReader = this._networkStream.getRangeReader(
        data.begin,
        data.end
      );