Changes based on review.

lib/elements/dom-if.js

@@ -255,11 +255,12 @@ export class DomIf extends PolymerElement {
       if (c$ && c$.length) {
         // use first child parent, for case when dom-if may have been detached
         let parent = wrap(c$[0]).parentNode;
-          // Instance children may be disconnected from parents when dom-if
-          // detaches if a tree was innerHTML'ed
-          if (parent) {
+        // Instance children may be disconnected from parents when dom-if
+        // detaches if a tree was innerHTML'ed
+        if (parent) {
+          parent = wrap(parent);
           for (let i=0, n; (i<c$.length) && (n=c$[i]); i++) {
-            wrap(parent).removeChild(n);
+            parent.removeChild(n);
           }
         }
       }

lib/elements/dom-repeat.js

@@ -324,9 +324,9 @@ export class DomRepeat extends domRepeatBase {
     // only perform attachment if the element was previously detached.
     if (this.__isDetached) {
       this.__isDetached = false;
-      let parent = wrap(this).parentNode;
+      let wrappedParent = wrap(wrap(this).parentNode);
       for (let i=0; i<this.__instances.length; i++) {
-        this.__attachInstance(i, parent);
+        this.__attachInstance(i, wrappedParent);
       }
     }
   }
@@ -584,16 +584,18 @@ export class DomRepeat extends domRepeatBase {
 
   __detachInstance(idx) {
     let inst = this.__instances[idx];
+    const wrappedRoot = wrap(inst.root);
     for (let i=0; i<inst.children.length; i++) {
       let el = inst.children[i];
-      wrap(inst.root).appendChild(el);
+      wrappedRoot.appendChild(el);
     }
     return inst;
   }
 
   __attachInstance(idx, parent) {
     let inst = this.__instances[idx];
-    wrap(parent).insertBefore(inst.root, this);
+    // Note, this is pre-wrapped as an optimization
+    parent.insertBefore(inst.root, this);
   }
 
   __detachAndRemoveInstance(idx) {

lib/legacy/legacy-element-mixin.js

@@ -482,9 +482,8 @@ export const LegacyElementMixin = dedupingMixin((base) => {
      * @return {Element} Element found by the selector, or null if not found.
      */
     $$(slctr) {
-      const root = /** @type {Element} */ (this.root);
-      const domApi = /** @type {DomApi} */(dom(root));
-      return domApi.querySelector(slctr);
+      // Note, no need to `wrap` this because root is always patched
+      return this.root.querySelector(slctr);
     }
 
     /**
@@ -607,9 +606,8 @@ export const LegacyElementMixin = dedupingMixin((base) => {
      * @return {!Array<!Node>} List of distributed nodes for the `<slot>`.
      */
     getContentChildNodes(slctr) {
-      const root = /** @type {Element} */ (this.root);
-        const domApi = /** @type {DomApi} */(dom(root));
-      let content = domApi.querySelector(slctr || 'slot');
+      // Note, no need to `wrap` this because root is always
+      let content = this.root.querySelector(slctr || 'slot');
       return content ? /** @type {DomApi} */(dom(content)).getDistributedNodes() : [];
     }