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

runtime/vm/flow_graph_compiler.cc

 // Copyright (c) 2013, 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"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 653 matching lines @@
     BeginCodeSourceRange();
     deopt_infos_[i]->GenerateCode(this, i);
     EndCodeSourceRange(TokenPosition::kDeferredDeoptInfo);
   }
 }
 
 
 void FlowGraphCompiler::AddExceptionHandler(intptr_t try_index,
                                             intptr_t outer_try_index,
                                             intptr_t pc_offset,
+                                            TokenPosition token_pos,
+                                            bool is_generated,
                                             const Array& handler_types,
                                             bool needs_stacktrace) {
   exception_handlers_list_->AddHandler(try_index, outer_try_index, pc_offset,
-                                       handler_types, needs_stacktrace);
+                                       token_pos, is_generated, handler_types,
+                                       needs_stacktrace);
 }
 
 
 void FlowGraphCompiler::SetNeedsStackTrace(intptr_t try_index) {
   exception_handlers_list_->SetNeedsStackTrace(try_index);
 }
 
 
 void FlowGraphCompiler::AddDescriptor(RawPcDescriptors::Kind kind,
                                       intptr_t pc_offset,
@@ skipping 1195 matching lines @@
 
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 
 }  // namespace dart