Enable causal stacktrace in kernel

runtime/vm/kernel.h

 // 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.
 
 #ifndef RUNTIME_VM_KERNEL_H_
 #define RUNTIME_VM_KERNEL_H_
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 #include "platform/assert.h"
 #include "vm/allocation.h"
@@ skipping 882 matching lines @@
   static FunctionNode* ReadFrom(Reader* reader);
 
   virtual ~FunctionNode();
 
   DEFINE_CASTING_OPERATIONS(FunctionNode);
 
   virtual void AcceptTreeVisitor(TreeVisitor* visitor);
   virtual void VisitChildren(Visitor* visitor);
 
   AsyncMarker async_marker() { return async_marker_; }
-  bool debuggable() { return debuggable_; }
+  AsyncMarker original_async_marker() { return original_async_marker_; }
   TypeParameterList& type_parameters() { return type_parameters_; }
   int required_parameter_count() { return required_parameter_count_; }
   List<VariableDeclaration>& positional_parameters() {
     return positional_parameters_;
   }
   List<VariableDeclaration>& named_parameters() { return named_parameters_; }
   DartType* return_type() { return return_type_; }
   InferredValue* inferred_return_value() { return inferred_return_value_; }
   Statement* body() { return body_; }
   TokenPosition position() { return position_; }
   TokenPosition end_position() { return end_position_; }
 
  private:
   FunctionNode()
       : position_(TokenPosition::kNoSource),
         end_position_(TokenPosition::kNoSource) {}
 
   AsyncMarker async_marker_;
-  bool debuggable_;
+  AsyncMarker original_async_marker_;
   TypeParameterList type_parameters_;
   int required_parameter_count_;
   List<VariableDeclaration> positional_parameters_;
   List<VariableDeclaration> named_parameters_;
   Child<DartType> return_type_;
   Child<InferredValue> inferred_return_value_;
   Child<Statement> body_;
   TokenPosition position_;
   TokenPosition end_position_;
 
@@ skipping 2234 matching lines @@
 
 kernel::Program* ReadPrecompiledKernelFromBuffer(const uint8_t* buffer,
                                                  intptr_t buffer_length);
 
 
 
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)
 #endif  // RUNTIME_VM_KERNEL_H_