handle xmlhook in mutation observer

examples/html-editor/index.js

@@ -1,4 +1,4 @@
-/* global Y, HTMLElement, customElements */
+/* global Y, HTMLElement, customElements, CanvasJS */
 
 window.onload = function () {
   window.yXmlType.bindToDom(document.body)
@@ -33,19 +33,18 @@ class MagicTable extends HTMLElement {
     var chart = new CanvasJS.Chart(this.shadowRoot,
       {
         title: {
-				text: "Bar chart"
+          text: 'Bar chart'
         },
-
         data: [
           {
-				type: "bar",
+            type: 'bar',
 
             dataPoints: dataPoints
           }
         ]
-		});
+      })
 
-		chart.render();
+    chart.render()
 
     // this.shadowRoot.innerHTML = '<p>dtrn</p>'
   }

src/Type/y-xml/YXmlFragment.js

@@ -268,7 +268,7 @@ export default class YXmlFragment extends YArray {
             mutations.forEach(mutation => {
               const dom = mutation.target
               const yxml = dom._yxml
-              if (yxml == null) {
+              if (yxml == null || yxml.constructor === YXmlHook) {
                 // dom element is filtered
                 return
               }