[debug] implement intuitive semantics for stepping over await call.

src/external-reference-table.cc

Index: src/external-reference-table.cc
diff --git a/src/external-reference-table.cc b/src/external-reference-table.cc
index 6b8b7d8efd642875040bcd5a88fa6bfff060c4bf..25ab73d59112e69edab9735ea4f57aef05fa9f75 100644
--- a/src/external-reference-table.cc
+++ b/src/external-reference-table.cc
@@ -191,6 +191,8 @@ ExternalReferenceTable::ExternalReferenceTable(Isolate* isolate) {
       "Debug::is_active_address()");
   Add(ExternalReference::debug_step_in_enabled_address(isolate).address(),
       "Debug::step_in_enabled_address()");
+  Add(ExternalReference::debug_suspended_generator_address(isolate).address(),
+      "Debug::step_suspended_generator_address()");
 
 #ifndef V8_INTERPRETED_REGEXP
   Add(ExternalReference::re_case_insensitive_compare_uc16(isolate).address(),