Await always waits

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 642 matching lines @@
 
   Instruction* previous() const { return previous_; }
   void set_previous(Instruction* instr) {
     ASSERT(!IsBlockEntry());
     previous_ = instr;
   }
 
   Instruction* next() const { return next_; }
   void set_next(Instruction* instr) {
     ASSERT(!IsGraphEntry());
-    ASSERT(!IsReturn());
     ASSERT(!IsBranch() || (instr == NULL));
     ASSERT(!IsPhi());
     ASSERT(instr == NULL || !instr->IsBlockEntry());
     // TODO(fschneider): Also add Throw and ReThrow to the list of instructions
     // that do not have a successor. Currently, the graph builder will continue
-    // to append instruction in case of a Throw inside an expression. This
-    // condition should be handled in the graph builder
+    // to append instructions in case of a Throw inside an expression. This
+    // condition should be handled in the graph builder.
+    // Note: there can be instructions after a return statement if the
+    // return is a "continuation return" in asynchronous code.
     next_ = instr;
   }
 
   // Link together two instruction.
   void LinkTo(Instruction* next) {
     ASSERT(this != next);
     this->set_next(next);
     next->set_previous(this);
   }
 
@@ skipping 7730 matching lines @@
       Isolate* isolate, bool opt) const {                                     \
     UNIMPLEMENTED();                                                          \
     return NULL;                                                              \
   }                                                                           \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_