Rework error handling in the service protocol and in Observatory.

runtime/observatory/lib/src/elements/code_view.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library code_view_element;
 
+import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
 import 'package:observatory/cpu_profile.dart';
 import 'package:polymer/polymer.dart';
 
 class DisassemblyTable extends SortedTable {
   DisassemblyTable(columns) : super(columns);
 }
@@ skipping 36 matching lines @@
     if (code == null) {
       return;
     }
     code.load().then((Code c) {
       c.loadScript();
       _updateDisassembly();
       _updateInline();
     });
   }
 
-  void refresh(var done) {
-    code.reload().whenComplete(done);
+  Future refresh() {
+    return code.reload();
   }
 
-  void refreshTicks(var done) {
+  Future refreshTicks() {
     var isolate = code.isolate;
-    isolate.invokeRpc('getCpuProfile', { 'tags': 'None' })
-      .then((ServiceMap response) {
-        var cpuProfile = new CpuProfile();
-        cpuProfile.load(isolate, response);
-        _updateDisassembly();
-        _updateInline();
-      }).whenComplete(done);
+    return isolate.invokeRpc('getCpuProfile', { 'tags': 'None' })
+        .then((ServiceMap response) {
+            var cpuProfile = new CpuProfile();
+            cpuProfile.load(isolate, response);
+            _updateDisassembly();
+            _updateInline();
+          });
   }
 
   String formattedAddress(CodeInstruction instruction) {
     if (instruction.address == 0) {
       return '';
     }
     return '0x${instruction.address.toRadixString(16)}';
   }
 
   String formattedAddressRange(CodeInlineInterval interval) {
@@ skipping 274 matching lines @@
   }
 
   void mouseOut(Event e, var detail, Node target) {
     var jt = _findJumpTarget(target);
     if (jt == null) {
       return;
     }
     jt.classes.remove('highlight');
   }
 }