Fixed build issue introduced with last commit.

runtime/vm/thread.cc

Index: runtime/vm/thread.cc
diff --git a/runtime/vm/thread.cc b/runtime/vm/thread.cc
index c91500be28d31e3e72ff043ba8e76a5a33fb4f88..23639d90f0a6c34966f6f195028165c935c36e43 100644
--- a/runtime/vm/thread.cc
+++ b/runtime/vm/thread.cc
@@ -212,7 +212,7 @@ void Thread::PrintJSON(JSONStream* stream) const {
   JSONObject jsobj(stream);
   jsobj.AddProperty("type", "_Thread");
   jsobj.AddPropertyF("id", "threads/%" Pd64 "",

[zra, 2016/12/12 18:36:35]

Now that we actually have an intptr_t. This can just be Pd instead of Pd64.

-                     ThreadIdToIntPtr(os_thread()->trace_id()));
+                     OSThread::ThreadIdToIntPtr(os_thread()->trace_id()));
   Zone* zone = zone_;
   {
     JSONArray zone_info_array(&jsobj, "zones");