fix getContainedComponents in IE 11

Author: KuroGuo

src/directives/if.js

@@ -88,9 +88,11 @@ module.exports = {
     function contains (c) {
       var cur = start
       var next
+      var isElementNode
       while (next !== end) {
         next = cur.nextSibling
-        if (cur.contains(c.$el)) {
+        isElementNode = cur.nodeType === Node.ELEMENT_NODE
+        if (isElementNode && cur.contains(c.$el)) {
           return true
         }
         cur = next