Minor Observatory UI tweaks.

runtime/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 {
         flex-grow: 1;
         font: 400 16px 'Montserrat', sans-serif;
       }
       .bigtextbox {
+        flex-grow: 1;
         font: 400 16px 'Montserrat', sans-serif;
       }
       .button {
         font: 400 16px 'Montserrat', sans-serif;
+        margin-left: 0.5em;
+        margin-right: 0.5em;
       }
       .radios {
         display: inline;
         padding-right: 30px;
       }
       .radios label{
         padding-left: 10px;
       }
       .historyExpr, .historyValue {
         vertical-align: text-top;
@@ skipping 29 matching lines @@
       }
       a.boxclose:hover {
         background: lightgray;
       }
     </style>
     <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"
+        <textarea class="bigtextbox"
                   value="{{ text }}"></textarea>
       </template>
 
       <input class="button" type="submit" value="Evaluate" on-click="{{ evaluate }}">
       <div class="radios" on-change="{{ updateLineMode }}">
         <label for="1-line">
           <input type="radio" name="lineMode" value="1-line" checked>
           1-line
         </label>
         <label for="N-line">
@@ skipping 28 matching lines @@
             <a class="boxclose" on-click="{{ closeItem }}"
                closeId="{{ result['id'] }}">&times;</a>
           </td>
         </tr>
       </table>
     </template>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="eval_box.dart"></script>