Cannot use `$if` together with setting `$state` from within `$lifecycle`

复现 issue 中的三个场景配置，对比 $if、$lifecycle post-load 和 $state.set。首先跟踪 framework 对 lifecycle、state 和 behavior 的处理，并查看相关 issue #41；当在 post-load 期间设置 path 能正确更新由 $if 控制的节点时，即表示完成。

In short, I can't use $if together with setting $state from within post-load.

This works:

FamousFramework.scene('ildar:page-controller', {
    behaviors: {
        // '#home': {
        //     '$if': function(path) { return path === '/'  }
        // },
        // '#blog': {
        //     '$if': function(path) { return path === '/blog'  }
        // },
        // '#about': {
        //     '$if': function(path) { return path === '/about' }
        // },
        '.page': {
            'size': [200, 200],
            'align': [0.5, 0.5],
            'mount-point': [0.5, 0.5],
            'style': {
                'background': 'whitesmoke'
            }
        }
    },
    events: {
        '$lifecycle': {
            'post-load': function($state) {
                console.log('post-load');
                $state.set('path', '/');
            }
        },
        '.page': {
            'click': function($state) {
                console.log('WORKS');
                $state.set('path', '/blog');
            }
        }
    },
    states: {
        path: null,
    },
    tree: `
        <node id="home"  class="page">  <div> HOME  </div>  </node>
        <node id="blog"  class="page">  <div> BLOG  </div>  </node>
        <node id="about" class="page">  <div> ABOUT </div>  </node>
    `
});

This also works:

FamousFramework.scene('ildar:page-controller', {
    behaviors: {
        '#home': {
            '$if': function(path) { return path === '/'  }
        },
        '#blog': {
            '$if': function(path) { return path === '/blog'  }
        },
        '#about': {
            '$if': function(path) { return path === '/about' }
        },
        '.page': {
            'size': [200, 200],
            'align': [0.5, 0.5],
            'mount-point': [0.5, 0.5],
            'style': {
                'background': 'whitesmoke'
            }
        }
    },
    events: {
        '$lifecycle': {
            'post-load': function($state) {
                console.log('post-load');
                // 
                // If $state isn't set from here, the code works.
                // 
                // $state.set('path', '/');
            }
        },
        '.page': {
            'click': function($state) {
                console.log('WORKS');
                $state.set('path', '/blog');
            }
        }
    },
    states: {
        path: '/',
    },
    tree: `
        <node id="home"  class="page">  <div> HOME  </div>  </node>
        <node id="blog"  class="page">  <div> BLOG  </div>  </node>
        <node id="about" class="page">  <div> ABOUT </div>  </node>
    `
});

But this doesn't work:

FamousFramework.scene('ildar:page-controller', {
    behaviors: {
        '#home': {
            '$if': function(path) { return path === '/'  }
        },
        '#blog': {
            '$if': function(path) { return path === '/blog'  }
        },
        '#about': {
            '$if': function(path) { return path === '/about' }
        },
        '.page': {
            'size': [200, 200],
            'align': [0.5, 0.5],
            'mount-point': [0.5, 0.5],
            'style': {
                'background': 'whitesmoke'
            }
        }
    },
    events: {
        '$lifecycle': {
            'post-load': function($state) {
                console.log('post-load');
                $state.set('path', '/');
            }
        },
        '.page': {
            'click': function($state) {
                console.log('WORKS');
                $state.set('path', '/blog');
            }
        }
    },
    states: {
        path: null,
    },
    tree: `
        <node id="home"  class="page">  <div> HOME  </div>  </node>
        <node id="blog"  class="page">  <div> BLOG  </div>  </node>
        <node id="about" class="page">  <div> ABOUT </div>  </node>
    `
});

Could be related to #41