Track async causal stack traces

runtime/vm/stub_code_dbc.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/globals.h"
 #if defined(TARGET_ARCH_DBC)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/cpu.h"
@@ skipping 77 matching lines @@
 void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   __ Trap();
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ Trap();
 }
 
 
+void StubCode::GenerateAsynchronousGapMarkerStub(Assembler* assembler) {
+  __ Trap();
+}
+
+
 // Print the stop message.
 DEFINE_LEAF_RUNTIME_ENTRY(void, PrintStopMessage, 1, const char* message) {
   OS::Print("Stop message: %s\n", message);
 }
 END_LEAF_RUNTIME_ENTRY
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC