fix(runtime-dom): support mounting app to svg container (#2929)

fix #2926

packages/runtime-dom/__tests__/createApp.spec.ts

@@ -0,0 +1,15 @@
+import { createApp, h } from '../src'
+
+describe('createApp for dom', () => {
+  // #2926
+  test('mount to SVG container', () => {
+    const root = document.createElementNS('http://www.w3.org/2000/svg', 'svg')
+    createApp({
+      render() {
+        return h('g')
+      }
+    }).mount(root)
+    expect(root.children.length).toBe(1)
+    expect(root.children[0] instanceof SVGElement).toBe(true)
+  })
+})

packages/runtime-dom/src/index.ts

@@ -69,7 +69,7 @@ export const createApp = ((...args) => {
     }
     // clear content before mounting
     container.innerHTML = ''
-    const proxy = mount(container)
+    const proxy = mount(container, false, container instanceof SVGElement)
     if (container instanceof Element) {
       container.removeAttribute('v-cloak')
       container.setAttribute('data-v-app', '')
@@ -92,7 +92,7 @@ export const createSSRApp = ((...args) => {
   app.mount = (containerOrSelector: Element | ShadowRoot | string): any => {
     const container = normalizeContainer(containerOrSelector)
     if (container) {
-      return mount(container, true)
+      return mount(container, true, container instanceof SVGElement)
     }
   }