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

runtime/vm/ast.h

 // Copyright (c) 2012, 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_AST_H_
 #define RUNTIME_VM_AST_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
@@ skipping 1783 matching lines @@
   LocalScope* scope_;
   const bool link_lazily_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(NativeBodyNode);
 };
 
 
 class CatchClauseNode : public AstNode {
  public:
   static const intptr_t kInvalidTryIndex = -1;
+  static const intptr_t kImplicitAsyncTryIndex = 0;
 
   CatchClauseNode(TokenPosition token_pos,
                   SequenceNode* catch_block,
                   const Array& handler_types,
                   const LocalVariable* context_var,
                   const LocalVariable* exception_var,
                   const LocalVariable* stacktrace_var,
                   const LocalVariable* rethrow_exception_var,
                   const LocalVariable* rethrow_stacktrace_var,
                   intptr_t catch_handler_index,
@@ skipping 160 matching lines @@
   const intptr_t try_index_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InlinedFinallyNode);
 };
 
 }  // namespace dart
 
 #undef DECLARE_COMMON_NODE_FUNCTIONS
 
 #endif  // RUNTIME_VM_AST_H_