Coalesce warnings for deprecated lifecycle hooks and print single message after reconciliation (rather than one per component-type).

Relates to PR #12028 and [this comment](https://github.com/facebook/react/pull/12028#discussion_r162420575).
unhandledError = error;
    }
  }
  // 
  // 
  function batchedUpdates<A, R>(fn: (a: A) => R, a: A): R {
    const previousIsBatchingUpdates = isBatchingUpdates;
    isBatchingUpdates = true;
    try {
      return fn(a);
    } finally {
      isBatchingUpdates = previousIsBatchingUpdates;
      if (!isBatchingUpdates && !isRendering) {
        performWork(Sync, null);
      }
    }
  }
  // 
  // 
  function unbatchedUpdates<A>(fn: () => A): A {
    if (isBatchingUpdates && !isUnbatchingUpdates) {
      isUnbatchingUpdates = true;
      try {
        return fn();
      } finally {
        isUnbatchingUpdates = false;
      }
    }
    return fn();
  }