Add dart:io view to the observatory.

runtime/vm/isolate.cc

 // 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.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
 #include "lib/mirrors.h"
@@ skipping 958 matching lines @@
     ASSERT(!error.IsNull());
     jsobj.AddProperty("error", error, false);
   }
 
   {
     JSONObject typeargsRef(&jsobj, "canonicalTypeArguments");
     typeargsRef.AddProperty("type", "@TypeArgumentsList");
     typeargsRef.AddProperty("id", "typearguments");
     typeargsRef.AddProperty("name", "canonical type arguments");
   }
+  bool is_io_enabled = false;
   {
     const GrowableObjectArray& libs =
         GrowableObjectArray::Handle(object_store()->libraries());
     intptr_t num_libs = libs.Length();
-    Library &lib = Library::Handle();
+    Library& lib = Library::Handle();
+    String& name = String::Handle();
 
     JSONArray lib_array(&jsobj, "libraries");
     for (intptr_t i = 0; i < num_libs; i++) {
       lib ^= libs.At(i);
+      name = lib.name();

[Cutch, 2014/05/23 05:51:37]

We should test the case when an imported library imports dart:io. I forget if
all libraries are flattened into this list.

[Anders Johnsen, 2014/05/23 05:59:13]

I checked, and they are. Do you want a actual test file - if so, where and how?

+      if (name.Equals(Symbols::DartIOLibName())) {
+        is_io_enabled = true;
+      }
       ASSERT(!lib.IsNull());
       lib_array.AddValue(lib);
     }
   }
+  {
+    JSONArray features_array(&jsobj, "features");
+    if (is_io_enabled) {
+      features_array.AddValue("io");
+    }
+  }
 }
 
 
 void Isolate::ProfileInterrupt() {
   InterruptableThreadState* state = thread_state();
   if (state == NULL) {
     // Isolate is not scheduled on a thread.
     ProfileIdle();
     return;
   }
@@ skipping 181 matching lines @@
   return func.raw();
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(isolate());
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart