Don't use a special var descriptor for :async_op since it can now be either stack or context alloca…

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 85568b84046b5574860f0ae5cfb08b54122e8ffe..770d1a92bd64ac3f0cb0b6e78699cb91550da963 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -927,12 +927,9 @@ static void DisassembleCode(const Function& function, bool optimized) {
       } else if (kind == RawLocalVarDescriptors::kStackVar) {
         THR_Print("  stack var '%s' offset %d",
           var_name.ToCString(), var_info.index());
-      } else if (kind == RawLocalVarDescriptors::kContextVar) {
-        THR_Print("  context var '%s' level %d offset %d",
-            var_name.ToCString(), var_info.scope_id, var_info.index());
       } else {
-        ASSERT(kind == RawLocalVarDescriptors::kAsyncOperation);
-        THR_Print("  async operation '%s' level %d offset %d",
+        ASSERT(kind == RawLocalVarDescriptors::kContextVar);
+        THR_Print("  context var '%s' level %d offset %d",
             var_name.ToCString(), var_info.scope_id, var_info.index());
       }
       THR_Print(" (valid %d-%d)\n", var_info.begin_pos, var_info.end_pos);