message: refactor: use isTrue
diff: @@ -132,7 +132,7 @@ function applyNS (vnode, ns, force) {
  if (isDef(vnode.children)) {
  for (let i = 0, l = vnode.children.length; i < l; i++) {
  const child = vnode.children[i]
  - if (isDef(child.tag) && (isUndef(child.ns) || force)) {
  + if (isDef(child.tag) && (isUndef(child.ns) || isTrue(force))) {
  applyNS(child, ns, force)
  }
  }
  