merge to trunk all changes from 36817 until 37378 under the packages: polymer,

pkg/polymer_expressions/lib/polymer_expressions.dart

Index: pkg/polymer_expressions/lib/polymer_expressions.dart
===================================================================
--- pkg/polymer_expressions/lib/polymer_expressions.dart	(revision 37373)
+++ pkg/polymer_expressions/lib/polymer_expressions.dart	(working copy)
@@ -143,8 +143,6 @@
       };
     }
 
-    // We have an ident, so it's a bind/as or repeat/in expression
-    assert(templateBind(template).templateInstance == null);
     return (model) {
       var existingScope = _scopes[template];
       if (existingScope != null) {
@@ -257,15 +255,13 @@
 typedef Object _Converter(Object);
 
 class _Binding extends Bindable {
-  static int __seq = 1;
-
-  final int _seq = __seq++;
-
   final Scope _scope;
   final _Converter _converter;
   final Expression _expr;
+
   Function _callback;
   StreamSubscription _sub;
+  ExpressionObserver _observer;
   var _value;
 
   _Binding(this._expr, this._scope, [converter])
@@ -311,19 +307,19 @@
     if (_callback != null) throw new StateError('already open');
 
     _callback = callback;
-    final expr = observe(_expr, _scope);
-//    _expr = expr;
-    _sub = expr.onUpdate.listen(_check)..onError((e, s) {
+    _observer = observe(_expr, _scope);
+    _sub = _observer.onUpdate.listen(_check)..onError((e, s) {
       new Completer().completeError(
-          "Error evaluating expression '$expr': $e", s);
+          "Error evaluating expression '$_observer': $e", s);
     });
+
     try {
       // this causes a call to _updateValue with the new value
-      update(expr, _scope);
-      _check(expr.currentValue, skipChanges: true);
+      update(_observer, _scope);
+      _check(_observer.currentValue, skipChanges: true);
     } catch (e, s) {
       new Completer().completeError(
-          "Error evaluating expression '$expr': $e", s);
+          "Error evaluating expression '$_observer': $e", s);
     }
     return _value;
   }
@@ -334,6 +330,9 @@
     _sub.cancel();
     _sub = null;
     _callback = null;
+
+    new Closer().visit(_observer);
+    _observer = null;
   }
 }