Polymer.dom: when adding a node, only remove the node from its existi…

…ng location if it's not a fragment and has a parent.

src/lib/dom-api-shady.html

@@ -55,12 +55,19 @@
         throw Error('The ref_node to be inserted before is not a child ' +
           'of this node');
       }
-      // notify existing parent that this node is being removed.
-      var parent = TreeApi.Logical.getParentNode(node);
-      if (parent && DomApi.hasApi(parent)) {
-        dom(parent).notifyObserver();
+      // remove node from its current position iff it's in a tree.
+      if (node.nodeType !== Node.DOCUMENT_FRAGMENT_NODE) {
+        var parent = TreeApi.Logical.getParentNode(node);
+        // notify existing parent that this node is being removed.
+        if (parent) {
+          if (DomApi.hasApi(parent)) {
+            dom(parent).notifyObserver();
+          }
+          this._removeNode(node);
+        } else {
+          this._removeOwnerShadyRoot(node);
+        }
       }
-      this._removeNode(node);
       if (!this._addNode(node, ref_node)) {
         if (ref_node) {
           // if ref_node is <content> replace with first distributed node