Add missing support in disassembler for recently introduced new variable

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 39fbf22d5725b89bc13e16c6dbe8c270baa7f804..4ba03785ec706b47db5e70c74b50857b4cc84ec6 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -932,10 +932,13 @@ static void DisassembleCode(const Function& function, bool optimized) {
       } else if (kind == RawLocalVarDescriptors::kStackVar) {
         ISL_Print("  stack var '%s' offset %d",
           var_name.ToCString(), var_info.index());
-      } else {
-        ASSERT(kind == RawLocalVarDescriptors::kContextVar);
+      } else if (kind == RawLocalVarDescriptors::kContextVar) {
         ISL_Print("  context var '%s' level %d offset %d",
             var_name.ToCString(), var_info.scope_id, var_info.index());
+      } else {
+        ASSERT(kind == RawLocalVarDescriptors::kAsyncOperation);
+        ISL_Print("  async operation '%s' level %d offset %d",
+            var_name.ToCString(), var_info.scope_id, var_info.index());
       }
       ISL_Print(" (valid %d-%d)\n", var_info.begin_pos, var_info.end_pos);
     }