fix(hmr): force full update in child component on slot update

packages/runtime-core/__tests__/hmr.spec.ts

@@ -45,7 +45,7 @@ describe('hot module replacement', () => {
 
     const Child: ComponentOptions = {
       __hmrId: childId,
-      render: compileToFunction(`<slot/>`)
+      render: compileToFunction(`<div><slot/></div>`)
     }
     createRecord(childId, Child)
 
@@ -62,13 +62,13 @@ describe('hot module replacement', () => {
     createRecord(parentId, Parent)
 
     render(h(Parent), root)
-    expect(serializeInner(root)).toBe(`<div>00</div>`)
+    expect(serializeInner(root)).toBe(`<div>0<div>0</div></div>`)
 
     // Perform some state change. This change should be preserved after the
     // re-render!
     triggerEvent(root.children[0] as TestElement, 'click')
     await nextTick()
-    expect(serializeInner(root)).toBe(`<div>11</div>`)
+    expect(serializeInner(root)).toBe(`<div>1<div>1</div></div>`)
 
     // // Update text while preserving state
     rerender(
@@ -77,7 +77,7 @@ describe('hot module replacement', () => {
         `<div @click="count++">{{ count }}!<Child>{{ count }}</Child></div>`
       )
     )
-    expect(serializeInner(root)).toBe(`<div>1!1</div>`)
+    expect(serializeInner(root)).toBe(`<div>1!<div>1</div></div>`)
 
     // Should force child update on slot content change
     rerender(
@@ -86,7 +86,7 @@ describe('hot module replacement', () => {
         `<div @click="count++">{{ count }}!<Child>{{ count }}!</Child></div>`
       )
     )
-    expect(serializeInner(root)).toBe(`<div>1!1!</div>`)
+    expect(serializeInner(root)).toBe(`<div>1!<div>1!</div></div>`)
 
     // Should force update element children despite block optimization
     rerender(
@@ -97,7 +97,7 @@ describe('hot module replacement', () => {
       </div>`
       )
     )
-    expect(serializeInner(root)).toBe(`<div>1<span>1</span>1!</div>`)
+    expect(serializeInner(root)).toBe(`<div>1<span>1</span><div>1!</div></div>`)
 
     // Should force update child slot elements
     rerender(
@@ -108,7 +108,7 @@ describe('hot module replacement', () => {
       </div>`
       )
     )
-    expect(serializeInner(root)).toBe(`<div><span>1</span></div>`)
+    expect(serializeInner(root)).toBe(`<div><div><span>1</span></div></div>`)
   })
 
   test('reload', async () => {