Await always waits

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
===================================================================
--- runtime/vm/intermediate_language.h	(revision 40777)
+++ runtime/vm/intermediate_language.h	(working copy)
@@ -660,14 +660,15 @@
   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;
   }