Late-bind filter and sort functions.

src/lib/template/dom-repeat.html

@@ -222,8 +222,9 @@ Then the `observe` property should be configured as follows:
 
     _sortChanged: function() {
       var dataHost = this._getRootDataHost();
-      this._sortFn = this.sort && (typeof this.sort == 'function' ?
-        this.sort : dataHost[this.sort].bind(dataHost));
+      var sort = this.sort;
+      this._sortFn = sort && (typeof sort == 'function' ? sort :
+        function() { return dataHost[sort].apply(dataHost, arguments); });
       this._fullRefresh = true;
       if (this.items) {
         this._debounceTemplate(this._render);
@@ -232,8 +233,9 @@ Then the `observe` property should be configured as follows:
 
     _filterChanged: function() {
       var dataHost = this._getRootDataHost();
-      this._filterFn = this.filter && (typeof this.filter == 'function' ?
-        this.filter : dataHost[this.filter].bind(dataHost));
+      var filter = this.filter;
+      this._filterFn = filter && (typeof filter == 'function' ? filter :
+        function() { return dataHost[filter].apply(dataHost, arguments); });
       this._fullRefresh = true;
       if (this.items) {
         this._debounceTemplate(this._render);

test/smoke/dom-bind.html

@@ -39,6 +39,18 @@
       </div>
     </template>
 
+    <h3>Show person by index, demonstrate filter</h3>
+    <template is="dom-repeat" items="{{employees}}" filter="onlyRob">
+      <div>
+        <div style="padding: 3px 0px;">
+          <button on-tap="modify">Modify</button>
+          <span>{{index}}</span>
+          <span>{{item.first}}</span>
+          <span>{{item.last}}</span>
+        </div>
+      </div>
+    </template>
+
   </template>
 
   <script>
@@ -50,6 +62,9 @@
     app.modify = function(e) {
       e.model.set('item.last', e.model.item.last + '*');
     };
+    app.onlyRob = function(item) {
+      return item.first == 'Rob';
+    };
     app.bar = true;
     app.employees = [
       {first: 'Bob', last: 'Smith'},