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

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 4802 matching lines @@
   // off immortal immovable roots to make sure they end up on the first page,
   // and then again for the rest.
   if (mode == VISIT_ONLY_STRONG_ROOT_LIST) return;
 
   isolate_->bootstrapper()->Iterate(v);
   v->Synchronize(VisitorSynchronization::kBootstrapper);
   isolate_->Iterate(v);
   v->Synchronize(VisitorSynchronization::kTop);
   Relocatable::Iterate(isolate_, v);
   v->Synchronize(VisitorSynchronization::kRelocatable);
+  isolate_->debug()->Iterate(v);
+  v->Synchronize(VisitorSynchronization::kDebug);
 
   isolate_->compilation_cache()->Iterate(v);
   v->Synchronize(VisitorSynchronization::kCompilationCache);
 
   // Iterate over local handles in handle scopes.
   isolate_->handle_scope_implementer()->Iterate(v);
   isolate_->IterateDeferredHandles(v);
   v->Synchronize(VisitorSynchronization::kHandleScope);
 
   // Iterate over the builtin code objects and code stubs in the
@@ skipping 1570 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8