Remove service.Class.children, and (mostly) as a side-effect sort the class hierarchy view.

runtime/bin/vmservice/observatory/deployed/web/index.html

Index: runtime/bin/vmservice/observatory/deployed/web/index.html
diff --git a/runtime/bin/vmservice/observatory/deployed/web/index.html b/runtime/bin/vmservice/observatory/deployed/web/index.html
index 6d50ef8d0abc2725ea8044be70b31b24ae63955c..1c6900f88eaf600b1346a406efdf21ed5b2a6fb1 100644
--- a/runtime/bin/vmservice/observatory/deployed/web/index.html
+++ b/runtime/bin/vmservice/observatory/deployed/web/index.html
@@ -4188,19 +4188,19 @@ hr {
 
         <div class="memberItem">&nbsp;</div>
 
-        <template if="{{ cls.superClass != null }}">
+        <template if="{{ cls.superclass != null }}">
           <div class="memberItem">
             <div class="memberName">extends</div>
             <div class="memberValue">
-              <class-ref ref="{{ cls.superClass }}"></class-ref>
+              <class-ref ref="{{ cls.superclass }}"></class-ref>
             </div>
           </div>
         </template>
-        <template if="{{ cls.subClasses.length > 0 }}">
+        <template if="{{ cls.subclasses.length > 0 }}">
           <div class="memberItem">
             <div class="memberName">extended by</div>
             <div class="memberValue">
-              <template repeat="{{ subclass in cls.subClasses }}">
+              <template repeat="{{ subclass in cls.subclasses }}">
                 <class-ref ref="{{ subclass }}"></class-ref>
               </template>
             </div>