Display multiline strings as multiline in Observatory's inspector.

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

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="class_ref.html">
 <link rel="import" href="error_view.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="inbound_reference.html">
 <link rel="import" href="instance_ref.html">
 <link rel="import" href="observatory_element.html">
@@ skipping 28 matching lines @@
         </template>
 
         <object-common object="{{ instance }}"></object-common>
 
         <div class="memberList">
           <div class="memberItem">&nbsp;</div>
 
           <template if="{{ instance.valueAsString != null }}">
             <div class="memberItem">
               <div class="memberName">value</div>
-              <div class="memberValue">{{ instance.valueAsString }}</div>
+              <div class="memberValue">
+                <pre>{{ instance.valueAsString }}</pre>
+              </div>
             </div>
           </template>
 
           <template if="{{ instance.isString }}">
             <div class="memberItem">
               <div class="memberName">valueAsLiteral</div>
               <div class="memberValue"> {{ asStringLiteral(instance.valueAsString, instance.valueAsStringIsTruncated) }}</div>
             </div>
           </template>
 
@@ skipping 121 matching lines @@
       </div>
 
       <br><br><br><br>
       <br><br><br><br>
 
     </template>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="instance_view.dart"></script>