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).
let instance;
    const Component = createReactClass({
      displayName: 'MyComponent',
      mixins: [
        {
          componentWillMount() {
            this.log('mixin.componentWillMount');
          },
          componentDidMount() {
            this.log('mixin.componentDidMount');
          },
          componentWillUpdate() {
            this.log('mixin.componentWillUpdate');
          },
          componentDidUpdate() {
            this.log('mixin.componentDidUpdate');
          },
          componentWillUnmount() {
            this.log('mixin.componentWillUnmount');
          },
        },
      ],
      log(name) {
        ops.push(`${name}: ${this.isMounted()}`);
      },
      getInitialState() {
        this.log('getInitialState');
        return {};
      },
      componentWillMount() {