observable.update now not subscribes.

observable.update now will not subscribe it's observable to the current
element (e.g. data-query).

src/query/observable.js

@@ -171,6 +171,8 @@ define([
           var isProperty;
           var propertyName;
 
+          Observer.startObserving();
+
           blocks.eachRight(this._expressions, function updateExpression(expression) {
             element = expression.element;
             context = expression.context;
@@ -246,6 +248,8 @@ define([
             observable(index);
           });
 
+          Observer.stopObserving();
+
           return this;
         },