build: add vue 2.x compat package

packages/vue/src/index.ts

@@ -0,0 +1,27 @@
+import { h, render, ComponentOptions } from '@vue/renderer-dom'
+
+function Vue(options: ComponentOptions & { el: any }) {
+  const { el, render: r } = options
+
+  if (r) {
+    options.render = function(props, slots) {
+      return r.call(this, h, props, slots)
+    }
+  }
+
+  function mount(el: any) {
+    const dom = document.querySelector(el)
+    render(h(options), dom)
+    return (dom as any).vnode.children.$proxy
+  }
+
+  if (el) {
+    return mount(el)
+  } else {
+    return {
+      $mount: mount
+    }
+  }
+}
+
+export default Vue