Improve class-tree, class-view, and instance-view.

runtime/observatory/lib/src/elements/class_view.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="action_link.html">
 <link rel="import" href="cpu_profile.html">
 <link rel="import" href="curly_block.html">
 <link rel="import" href="eval_box.html">
 <link rel="import" href="eval_link.html">
 <link rel="import" href="field_ref.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="library_ref.html">
@@ skipping 17 matching lines @@
     </nav-bar>
 
     <div class="content">
       <h1>
         <template if="{{ cls.isAbstract }}">
           abstract
         </template>
         <template if="{{ cls.isPatch }}">
           patch
         </template>
+        <template if="{{ cls.mixin != null }}">
+          mixin
+        </template>
         class {{ cls.name }}
       </h1>
 
       <object-common object="{{ cls }}"></object-common>
       <br>
 
       <div class="memberList">
         <div class="memberItem">
           <div class="memberName">library</div>
           <div class="memberValue">
             <library-ref ref="{{ cls.library }}"></library-ref>
           </div>
         </div>
         <div class="memberItem">
           <div class="memberName">script</div>
           <div class="memberValue">
             <source-link location="{{ cls.location }}"></source-link>
           </div>
         </div>
 
         <div class="memberItem">&nbsp;</div>
 
         <template if="{{ cls.superclass != null }}">
           <div class="memberItem">
-            <div class="memberName">extends</div>
+            <div class="memberName">superclass</div>
             <div class="memberValue">
               <class-ref ref="{{ cls.superclass }}"></class-ref>
             </div>
           </div>
         </template>
+        <template if="{{ cls.superType != null }}">
+          <div class="memberItem">
+            <div class="memberName">supertype</div>
+            <div class="memberValue">
+              <instance-ref ref="{{ cls.superType }}"></instance-ref>
+            </div>
+          </div>
+        </template>
+        <template if="{{ cls.mixin != null }}">
+          <div class="memberItem">
+            <div class="memberName">mixin</div>
+            <div class="memberValue">
+              <instance-ref ref="{{ cls.mixin }}"></instance-ref>
+            </div>
+          </div>
+        </template>
         <template if="{{ cls.subclasses.length > 0 }}">
           <div class="memberItem">
             <div class="memberName">extended by</div>
             <div class="memberValue">
               <template repeat="{{ subclass in cls.subclasses }}">
                 <class-ref ref="{{ subclass }}"></class-ref>
               </template>
             </div>
           </div>
         </template>
@@ skipping 182 matching lines @@
       <hr>
       <source-inset location="{{ cls.location }}">
       </source-inset>
     </div>
 
     <view-footer></view-footer>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="class_view.dart"></script>