__patch__ => patch$mount检测devtools
_init
重新定义config内置函数混入全局的指令和组件到Vue.options里面
保存原来$mount，重新定义$mount
$data => _data$props => _props$set$delete$watch
prototype
$on$once$off$emit
function Vue()
_update$forceUpdate$destroy
_x等方法$nextTick_render
$isServer$ssrContextFunctionalRenderContext
