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).
return shouldUpdate;
    }
    if (type.prototype && type.prototype.isPureReactComponent) {
      return (
        !shallowEqual(oldProps, newProps) || !shallowEqual(oldState, newState)
      );
    }
    return true;
  }
  function checkClassInstance(workInProgress: Fiber) {
    const instance = workInProgress.stateNode;
    const type = workInProgress.type;
    if (__DEV__) {
      const name = getComponentName(workInProgress);
      const renderPresent = instance.render;
      if (!renderPresent) {
        if (type.prototype && typeof type.prototype.render === 'function') {
          warning(
            false,
            '%s(...): No `render` method found on the returned component ' +
              'instance: did you accidentally return an object from the constructor?',
            name,
          );
        } else {
          warning(
            false,
            '%s(...): No `render` method found on the returned component ' +
              'instance: you may have forgotten to define `render`.',
            name,
          );