Track the 'awaiter return' call stack use it to detect uncaught exceptions in async functions

runtime/vm/object_service.cc

 // Copyright (c) 2016, 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/debugger.h"
 #include "vm/disassembler.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ skipping 851 matching lines @@
   const PcDescriptors& descriptors = PcDescriptors::Handle(pc_descriptors());
   if (!descriptors.IsNull()) {
     JSONObject desc(&jsobj, "_descriptors");
     descriptors.PrintToJSONObject(&desc, false);
   }
 
   PrintJSONInlineIntervals(&jsobj);
 }
 
 
+void Code::SetAwaitTokenPositions(const Array& await_token_positions) const {
+  StorePointer(&raw_ptr()->await_token_positions_, await_token_positions.raw());
+}
+
+
 void Context::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   // TODO(turnidge): Should the user level type for Context be Context
   // or Object?
   AddCommonObjectProperties(&jsobj, "Context", ref);
   jsobj.AddServiceId(*this);
 
   jsobj.AddProperty("length", num_variables());
 
   if (ref) {
@@ skipping 674 matching lines @@
   jsobj.AddProperty("mirrorReferent", referent_handle);
 }
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 #endif
 
 }  // namespace dart