Revert "fix nested bindings"

pkg/polymer_expressions/lib/polymer_expressions.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A binding delegate used with Polymer elements that
  * allows for complex binding expressions, including
  * property access, function invocation,
  * list/map indexing, and two-way filtering.
  *
@@ skipping 52 matching lines @@
    * variables used as [globals]. If no globals are supplied, a copy of the
    * [DEFAULT_GLOBALS] will be used.
    */
   PolymerExpressions({Map<String, Object> globals})
       : globals = (globals == null) ?
           new Map<String, Object>.from(DEFAULT_GLOBALS) : globals;
 
   prepareBinding(String path, name, node) {
     if (path == null) return null;
     var expr = new Parser(path).parse();
-
-    // For template bind/repeat to an empty path, just pass through the model.
-    // We don't want to unwrap the Scope.
-    // TODO(jmesserly): a custom element extending <template> could notice this
-    // behavior. An alternative is to associate the Scope with the node via an
-    // Expando, which is what the JavaScript PolymerExpressions does.
-    if (isSemanticTemplate(node) && (name == 'bind' || name == 'repeat') &&
-        expr is EmptyExpression) {
-      return null;
-    }
-
     return (model, node) {
       if (model is! Scope) {
         model = new Scope(model: model, variables: globals);
       }
       if (node is Element && name == "class") {
         return new _Binding(expr, model, _classAttributeConverter);
       }
       if (node is Element && name == "style") {
         return new _Binding(expr, model, _styleAttributeConverter);
       }
@@ skipping 45 matching lines @@
   @reflectable get value => _value;
 
   @reflectable set value(v) {
     try {
       assign(_expr, v, _scope);
     } on EvalException catch (e) {
       _logger.warning("Error evaluating expression '$_expr': ${e.message}");
     }
   }
 }