Make local variables sticky-scroll in debugger frames.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="function_ref.html">
 <link rel="import" href="nav_bar.html">
 <link rel="import" href="eval_link.html">
 <link rel="import" href="observatory_element.html">
 <link rel="import" href="script_inset.html">
 <link rel="import" href="script_ref.html">
 
 <!-- TODO(turnidge): Use core-icon once core_elements work properly in
      devtools -->
@@ skipping 220 matching lines @@
         flex-grow: 1;
         flex-shrink: 1;
         flex-basis: 765px;
       }
       .flex-item-vars {
         flex-grow: 5;
         flex-shrink: 0;
         flex-basis: 250px;
         overflow-x: hidden;
       }
+      #vars {
+        position: relative;
+        top: 5px;
+        padding-left:2em;
+        padding-bottom: 5px;
+      }
     </style>
     <div id="frameOuter" class="frameOuter">
       <a on-click="{{ toggleExpand }}">
         <div class="frameSummary">
           <div class="frameSummaryText">
             <div class="frameId"><b>frame {{ frame.index }}</b></div>
             <function-ref ref="{{ frame.function }}"></function-ref>
             ( <source-link location="{{ frame.location }}"></source-link> )
           </div>
           <template if="{{ !expanded }}">
@@ skipping 10 matching lines @@
             <div class="flex-item-script">
               <source-inset height="{{ scriptHeight }}"
                             location="{{ frame.function.location }}"
                             currentPos="{{ frame.location.tokenPos }}"
                             inDebuggerContext="{{ true }}"
                             scroller="{{ scroller }}"
                             variables="{{ frame.variables }}">
               </source-inset>
             </div>
             <div class="flex-item-vars">
-              <div style="padding-left:2em;" class="memberList">
+              <div id="vars" class="memberList">
                 <template repeat="{{ v in properLocals }}">
                   {{ v['name']}}&nbsp;:&nbsp;
                   <any-service-ref ref="{{ v['value'] }}"
                                    expandKey="{{ makeExpandKey(v['name']) }}"
                                    asValue="{{ true }}">
                   </any-service-ref><br>
                 </template>
               </div>
             </div>
           </div>
@@ skipping 184 matching lines @@
     <div class="container">
       <template if="{{ modalPrompt != null }}">
         <div class="modalPrompt">{{ modalPrompt }}</div>
       </template>
       <input id="textBox" class="textBox" type="text" value="{{ text }}" autofocus>
     </div>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="debugger.dart"></script>