[ES6 modules] ModuleMap::GetFetchedModuleScript to return nullptr when entry not found / "fetching"

third_party/WebKit/Source/core/dom/Modulator.h

Index: third_party/WebKit/Source/core/dom/Modulator.h
diff --git a/third_party/WebKit/Source/core/dom/Modulator.h b/third_party/WebKit/Source/core/dom/Modulator.h
index 2e6260fefd3952a3c112dbc8210f8d1b39f3d1fb..41b4ff84eb7b349c9e32f46369322c7be9f20ded 100644
--- a/third_party/WebKit/Source/core/dom/Modulator.h
+++ b/third_party/WebKit/Source/core/dom/Modulator.h
@@ -92,7 +92,8 @@ class CORE_EXPORT Modulator : public GarbageCollectedFinalized<Modulator>,
 
   // Synchronously retrieves a single module script from existing module map
   // entry.
-  // Note: returns nullptr if the module map entry is still "fetching".
+  // Note: returns nullptr if the module map entry doesn't exist, or
+  // is still "fetching".
   virtual ModuleScript* GetFetchedModuleScript(const KURL&) = 0;
 
   // https://html.spec.whatwg.org/#resolve-a-module-specifier