Propagate the stack trace of the inner-most throw when using async/await.

runtime/vm/ast_transformer.cc

 // Copyright (c) 2014, 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/ast_transformer.h"
 
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/thread.h"
 
@@ skipping 113 matching lines @@
   //
   //   :saved_try_ctx_var = :await_saved_try_ctx_var_y;
   //   :await_temp_var_(X+1) = :result_param;
 
   LocalVariable* async_op = GetVariableInScope(
       preamble_->scope(), Symbols::AsyncOperation());
   LocalVariable* result_param = GetVariableInScope(
       preamble_->scope(), Symbols::AsyncOperationParam());
   LocalVariable* error_param = GetVariableInScope(
       preamble_->scope(), Symbols::AsyncOperationErrorParam());
+  LocalVariable* stack_trace_param = GetVariableInScope(
+      preamble_->scope(), Symbols::AsyncOperationStackTraceParam());
 
   AstNode* transformed_expr = Transform(node->expr());
   preamble_->Add(new(Z) StoreLocalNode(
       Scanner::kNoSourcePos, result_param, transformed_expr));
 
   LoadLocalNode* load_result_param = new(Z) LoadLocalNode(
       Scanner::kNoSourcePos, result_param);
 
   const Class& future_cls =
       Class::ZoneHandle(Z, thread()->isolate()->object_store()->future_class());
@@ skipping 73 matching lines @@
     LocalVariable* async_saved_try_ctx =
         GetVariableInScope(preamble_->scope(), async_saved_try_ctx_name);
     preamble_->Add(new (Z) StoreLocalNode(
         Scanner::kNoSourcePos,
         parsed_function_.saved_try_ctx(),
         new (Z) LoadLocalNode(Scanner::kNoSourcePos, async_saved_try_ctx)));
   }
 
   LoadLocalNode* load_error_param = new (Z) LoadLocalNode(
       Scanner::kNoSourcePos, error_param);
+  LoadLocalNode* load_stack_trace_param = new (Z) LoadLocalNode(
+      Scanner::kNoSourcePos, stack_trace_param);
   SequenceNode* error_ne_null_branch = new (Z) SequenceNode(
       Scanner::kNoSourcePos, ChainNewScope(preamble_->scope()));
   error_ne_null_branch->Add(new (Z) ThrowNode(
       Scanner::kNoSourcePos,
       load_error_param,
-      NULL));
+      load_stack_trace_param));
   preamble_->Add(new (Z) IfNode(
       Scanner::kNoSourcePos,
       new (Z) ComparisonNode(
           Scanner::kNoSourcePos,
           Token::kNE,
           load_error_param,
           new (Z) LiteralNode(Scanner::kNoSourcePos,
                               Object::null_instance())),
           error_ne_null_branch,
           NULL));
@@ skipping 352 matching lines @@
 void AwaitTransformer::VisitThrowNode(ThrowNode* node) {
   // TODO(mlippautz): Check if relevant.
   AstNode* new_exception = Transform(node->exception());
   AstNode* new_stacktrace = Transform(node->stacktrace());
   result_ = new(Z) ThrowNode(node->token_pos(),
                              new_exception,
                              new_stacktrace);
 }
 
 }  // namespace dart