[modules] Don't throw when detecting cycle while processing star exports.

src/objects.h

 // Copyright 2015 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 7971 matching lines @@
   static const int kSize = kEmbedderDataOffset + kPointerSize;
 
  private:
   enum { kEvaluatedBit };
 
   static void CreateExport(Handle<Module> module, Handle<FixedArray> names);
   static void CreateIndirectExport(Handle<Module> module, Handle<String> name,
                                    Handle<ModuleInfoEntry> entry);
 
   // The [must_resolve] argument indicates whether or not an exception should be
-  // thrown if the module does not provide an export named [name].
+  // thrown in case the module does not provide an export named [name]
+  // (including when a cycle is detected).  An exception is always thrown in the
+  // case of conflicting star exports.
   //
   // If [must_resolve] is true, a null result indicates an exception. If
-  // [must_resolve] is false, a null result does not necessarily indicate an
-  // exception, but there may be one pending.
-  //
-  // Currently, an exception is always thrown in the case of a cycle and in the
-  // case of conflicting star exports.  TODO(neis): Make that spec-compliant.
+  // [must_resolve] is false, a null result may or may not indicate an
+  // exception (so check manually!).
   class ResolveSet;
   static MUST_USE_RESULT MaybeHandle<Cell> ResolveExport(
       Handle<Module> module, Handle<String> name, bool must_resolve,
       ResolveSet* resolve_set);
   static MUST_USE_RESULT MaybeHandle<Cell> ResolveImport(
       Handle<Module> module, Handle<String> name, int module_request,
       bool must_resolve, ResolveSet* resolve_set);
 
   // Helper for ResolveExport.
   static MUST_USE_RESULT MaybeHandle<Cell> ResolveExportUsingStarExports(
@@ skipping 3439 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_