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

src/runtime/runtime-generator.cc

Index: src/runtime/runtime-generator.cc
diff --git a/src/runtime/runtime-generator.cc b/src/runtime/runtime-generator.cc
index 1245ff14fbe8c8aed4bda00b5538728154e5b83b..e201c49fc6fe877b9f36f48e72866158685f6089 100644
--- a/src/runtime/runtime-generator.cc
+++ b/src/runtime/runtime-generator.cc
@@ -5,6 +5,7 @@
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
+#include "src/debug/debug.h"
 #include "src/factory.h"
 #include "src/frames-inl.h"
 #include "src/objects-inl.h"
@@ -51,6 +52,10 @@ RUNTIME_FUNCTION(Runtime_SuspendJSGeneratorObject) {
   DCHECK(frame->function()->shared()->is_compiled());
   DCHECK(!frame->function()->IsOptimized());
 
+  if (generator_object->function()->shared()->is_async()) {
+    isolate->debug()->RecordAsyncFunction(generator_object);
+  }
+
   // The caller should have saved the context and continuation already.
   DCHECK_EQ(generator_object->context(), Context::cast(frame->context()));
   DCHECK_LT(0, generator_object->continuation());