[top-level-await] Make Module::IsGraphAsync const

Bug: v8:9344
Change-Id: Id91afc60989afd45c4c0d00696afb4c81489f0ee
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2458146
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70398}

src/objects/module.cc

@@ -371,7 +371,7 @@ Maybe<PropertyAttributes> JSModuleNamespace::GetPropertyAttributes(
   return Just(it->property_attributes());
 }
 
-bool Module::IsGraphAsync(Isolate* isolate) {
+bool Module::IsGraphAsync(Isolate* isolate) const {
   DisallowGarbageCollection no_gc;
 
   // Only SourceTextModules may be async.

src/objects/module.h

@@ -65,7 +65,7 @@ class Module : public HeapObject {
 
   // Returns if this module or any transitively requested module is [[Async]],
   // i.e. has a top-level await.
-  V8_WARN_UNUSED_RESULT bool IsGraphAsync(Isolate* isolate);
+  V8_WARN_UNUSED_RESULT bool IsGraphAsync(Isolate* isolate) const;
 
   // Implementation of spec operation ModuleDeclarationInstantiation.
   // Returns false if an exception occurred during instantiation, true