message: refactor(tap): rename DoOperator to TapOperator
diff: @@ -69,11 +69,11 @@ export function tap<T>(nextOrObserver?: PartialObserver<T> | ((x: T) => void) |
  error?: ((e: any) => void) | null,
  complete?: (() => void) | null): MonoTypeOperatorFunction<T> {
  return function tapOperatorFunction(source: Observable<T>): Observable<T> {
  - return lift(source, new DoOperator(nextOrObserver, error, complete));
  + return lift(source, new TapOperator(nextOrObserver, error, complete));
  };
  }
  -class DoOperator<T> implements Operator<T, T> {
  +class TapOperator<T> implements Operator<T, T> {
  constructor(private nextOrObserver?: PartialObserver<T> | ((x: T) => void) | null,
  private error?: ((e: any) => void) | null,
  private complete?: (() => void) | null) {
  