Updated Tracker to deal with Polymer element restrictions

samples/tracker/web/elements/task_form_element.html

Index: samples/tracker/web/elements/task_form_element.html
diff --git a/samples/tracker/web/elements/task_form_element.html b/samples/tracker/web/elements/task_form_element.html
index 336341a6fa2c0936aca946835d3c8bcdef228fef..a5c46dcfdf9adbb2ff44cd3872e96d6426e3d722 100644
--- a/samples/tracker/web/elements/task_form_element.html
+++ b/samples/tracker/web/elements/task_form_element.html
@@ -30,7 +30,7 @@ BSD-style license that can be found in the LICENSE file.
 
     <form on-submit="{{createOrUpdateTask}}">
       <!-- Can't delete a form for creating a new task. -->
-      <template if="{{task.saved}}">
+      <template if="{{taskSaved}}">
         <div on-click="{{deleteTask}}"
             class="delete-task glyphicon glyphicon-remove"></div>
       </template>
@@ -38,9 +38,9 @@ BSD-style license that can be found in the LICENSE file.
       <div class="field">
         <textarea class="form-control" placeholder="Add title here"
             value="{{task.title}}" on-keyup="{{validateTitle}}"></textarea>
-        <span class="chars-left">{{maxTitleLength - task.title.length}}</span>
+        <span class="chars-left">{{maxTitleLength - taskTitleLength}}</span>
 
-        <div class="error" hidden?="{{titleErrorMessage.isEmpty}}">
+        <div class="error" hidden?="{{titleErrorMessageIsEmpty}}">
           {{titleErrorMessage}}
         </div>
       </div>
@@ -50,10 +50,10 @@ BSD-style license that can be found in the LICENSE file.
             placeholder="Add description here" value="{{task.description}}"
             on-keyup="{{validateDescription}}"></textarea>
         <span class="chars-left">
-          {{maxDescriptionLength - task.description.length}}
+          {{maxDescriptionLength - taskDescriptionLength}}
         </span>
 
-        <div class="error" hidden?="{{descriptionErrorMessage.isEmpty}}">
+        <div class="error" hidden?="{{descriptionErrorMessageIsEmpty}}">
           {{descriptionErrorMessage}}
         </div>
       </div>