Teach the Observatory about Contexts. Factor out object graph information from the instance view.

runtime/bin/vmservice/observatory/lib/src/elements/eval_box.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="error_ref.html">
 <link rel="import" href="observatory_element.html">
 
 <polymer-element name="eval-box" extends="observatory-element">
   <template>
     <style>
       .textbox {
-        width: 80ex;
+        flex-grow: 1;
         font: 400 16px 'Montserrat', sans-serif;
       }
       .bigtextbox {
         font: 400 16px 'Montserrat', sans-serif;
       }
       .button {
         font: 400 16px 'Montserrat', sans-serif;
       }
       .radios {
         display: inline;
+        padding-right: 30px;
       }
       .radios label{
-        padding-left: 15px;
+        padding-left: 10px;
       }
       .historyExpr, .historyValue {
         vertical-align: text-top;
         font: 400 14px 'Montserrat', sans-serif;
       }
       .historyExpr a {
         display: block;
         color: black;
         text-decoration: none;
         padding: 6px 6px;
         cursor: pointer;
         white-space: pre-line;
       }
       .historyExpr a:hover {
         background-color: #fff3e3;
       }
       .historyValue {
         display: block;
         padding: 6px 6px;
       }
     </style>
-    <form>
+    <form style="display:flex; flex-direction:row; align-items:flex-end">
       <template if="{{ lineMode == '1-line' }}">
         <input class="textbox" type="text" value="{{ text }}">
       </template>
       <template if="{{ lineMode == 'N-line' }}">
         <textarea class="bigtextbox" rows="5" cols="80"
                   value="{{ text }}"></textarea>
       </template>
 
       <input class="button" type="submit" value="Evaluate" on-click="{{ eval }}">
       <div class="radios" on-change="{{ updateLineMode }}">
-        <label for="1-line">1-line
+        <label for="1-line">
           <input type="radio" name="lineMode" value="1-line" checked>
+          1-line
         </label>
-        <label for="N-line">N-line
+        <label for="N-line">
           <input type="radio" name="lineMode" value="N-line">
+          N-line
         </label>
       </div>
     </form>
 
     <br>
     <template if="{{ results.isNotEmpty }}">
       <table>
         <tr template repeat="{{ result in results }}">
           <td class="historyExpr">
             <a class="expr" on-click="{{ selectExpr }}"
                expr="{{ result['expr'] }}">{{ result['expr'] }}</a>
           </td>
           <td class="historyValue">
             <template if="{{ result['value'] == null }}">
               <div style="color:#aaa;cursor:wait;">&lt;pending&gt;</div>
             </template>
             <template if="{{ result['value'] != null }}">
               <any-service-ref ref="{{ result['value'] }}"></any-service-ref>
             </template>
           </td>
         </tr>
       </table>
     </template>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="eval_box.dart"></script>