Add request tracing to Observatory:

runtime/bin/vmservice/client/lib/src/elements/stack_frame.html

Index: runtime/bin/vmservice/client/lib/src/elements/stack_frame.html
diff --git a/runtime/bin/vmservice/client/lib/src/elements/stack_frame.html b/runtime/bin/vmservice/client/lib/src/elements/stack_frame.html
index 8cb6e9aac46930aa8046c877e946e816bf3c26ad..b48efbddaf002822e7d87798d60dc1a6785008f9 100644
--- a/runtime/bin/vmservice/client/lib/src/elements/stack_frame.html
+++ b/runtime/bin/vmservice/client/lib/src/elements/stack_frame.html
@@ -16,11 +16,12 @@
       </div>
       <div class="flex-item-fixed-9-12">
         <function-ref ref="{{ frame['function'] }}"></function-ref>
-          ( <script-ref ref="{{ frame['script'] }}"
+        ( <script-ref ref="{{ frame['script'] }}"
                         pos="{{ frame['tokenPos'] }}">
-          </script-ref> )
+        </script-ref> )
 
-          <curly-block>
+        <curly-block callback="{{ expander() }}">
+          <template if="{{ expand }}">
             <div class="memberList">
               <template repeat="{{ v in frame['vars'] }}">
                 <div class="memberItem">
@@ -31,7 +32,8 @@
                 </div>
               </template>
             </div>
-          </curly-block>
+          </template>
+        </curly-block>
       </div>
       <div class="flex-item-fixed-1-12">
       </div>
@@ -39,4 +41,4 @@
   </template>
 </polymer-element>
 
-<script type="application/dart" src="stack_frame.dart"></script>
+<script type="application/dart" src="stack_frame.dart"></script>