feat(runtime-dom): support using mount target innerHTML as template

packages/runtime-core/src/apiApp.ts

@@ -18,7 +18,7 @@ export interface App<HostElement = any> {
   directive(name: string, directive: Directive): this
   mount(
     rootComponent: Component,
-    rootContainer: HostElement,
+    rootContainer: HostElement | string,
     rootProps?: Data
   ): ComponentPublicInstance
   provide<T>(key: InjectionKey<T> | string, value: T): void
@@ -141,7 +141,7 @@ export function createAppAPI<HostNode, HostElement>(
 
       mount(
         rootComponent: Component,
-        rootContainer: string | HostElement,
+        rootContainer: HostElement,
         rootProps?: Data
       ): any {
         if (!isMounted) {

packages/runtime-core/src/createRenderer.ts

@@ -123,7 +123,7 @@ export interface RendererOptions<HostNode = any, HostElement = any> {
 
 export type RootRenderFunction<HostNode, HostElement> = (
   vnode: VNode<HostNode, HostElement> | null,
-  dom: HostElement | string
+  dom: HostElement
 ) => void
 
 /**
@@ -1858,19 +1858,12 @@ export function createRenderer<
     }
   }
 
-  function render(vnode: HostVNode | null, rawContainer: HostElement | string) {
-    let container: any = rawContainer
-    if (isString(container)) {
-      container = hostQuerySelector(container)
-      if (!container) {
-        if (__DEV__) {
-          warn(
-            `Failed to locate root container: ` + `querySelector returned null.`
-          )
-        }
-        return
-      }
+  const render: RootRenderFunction<
+    HostNode,
+    HostElement & {
+      _vnode: HostVNode | null
     }
+  > = (vnode, container) => {
     if (vnode == null) {
       if (container._vnode) {
         unmount(container._vnode, null, null, true)