Don't delay values and errors from async/await functions.

runtime/vm/symbols.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 VM_SYMBOLS_H_
 #define VM_SYMBOLS_H_
 
 #include "vm/object.h"
 #include "vm/snapshot_ids.h"
 
@@ skipping 101 matching lines @@
   V(AwaitContextVar, ":await_ctx_var")                                         \
   V(AwaitJumpVar, ":await_jump_var")                                           \
   V(Future, "Future")                                                          \
   V(FutureMicrotask, "Future.microtask")                                       \
   V(FutureValue, "Future.value")                                               \
   V(FutureThen, "then")                                                        \
   V(FutureCatchError, "catchError")                                            \
   V(Completer, "Completer")                                                    \
   V(CompleterComplete, "complete")                                             \
   V(CompleterCompleteError, "completeError")                                   \
-  V(CompleterConstructor, "Completer.")                                        \
+  V(CompleterSyncConstructor, "Completer.sync")                                \
   V(CompleterFuture, "future")                                                 \
   V(StreamIterator, "StreamIterator")                                          \
   V(StreamIteratorConstructor, "StreamIterator.")                              \
   V(Native, "native")                                                          \
   V(Class, "Class")                                                            \
   V(Null, "Null")                                                              \
   V(Dynamic, "dynamic")                                                        \
   V(UnresolvedClass, "UnresolvedClass")                                        \
   V(Type, "_Type")                                                             \
   V(TypeRef, "_TypeRef")                                                       \
@@ skipping 499 matching lines @@
   friend class SnapshotReader;
   friend class SnapshotWriter;
   friend class ApiMessageReader;
 
   DISALLOW_COPY_AND_ASSIGN(Symbols);
 };
 
 }  // namespace dart
 
 #endif  // VM_SYMBOLS_H_