message: Fixing type info for Container.on() method
diff: @@ -208,10 +208,11 @@ export class Container extends EventEmitter implements IContainer {
  }
  public on(event: "connected" | "contextChanged", listener: (clientId: string) => void): this;
  - public on(event: "disconnect", listener: () => void): this;
  + public on(event: "disconnected", listener: () => void): this;
  public on(event: "error", listener: (error: any) => void): this;
  public on(event: "op", listener: (message: ISequencedDocumentMessage) => void): this;
  public on(event: "pong" | "processTime", listener: (latency: number) => void): this;
  + public on(event: MessageType.BlobUploaded, listener: (contents: any) => void): this;
  /* tslint:disable:no-unnecessary-override */
  public on(event: string | symbol, listener: (...args: any[]) => void): this {
  