[modules] Allow resolve-callback to signal failure.

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 6706 matching lines @@
   DECL_ACCESSORS(requested_modules, FixedArray)
 
   // Get the ModuleInfo associated with the code.
   inline ModuleInfo* info() const;
 
   inline bool instantiated() const;
   inline bool evaluated() const;
 
   // Implementation of spec operation ModuleDeclarationInstantiation.
   // Returns false if an exception occurred during instantiation, true
-  // otherwise.
+  // otherwise. (In the case where the callback throws an exception, that
+  // exception is propagated.)
   static MUST_USE_RESULT bool Instantiate(Handle<Module> module,
                                           v8::Local<v8::Context> context,
                                           v8::Module::ResolveCallback callback);
 
   // Implementation of spec operation ModuleEvaluation.
   static MUST_USE_RESULT MaybeHandle<Object> Evaluate(Handle<Module> module);
 
   static Handle<Object> LoadVariable(Handle<Module> module, int cell_index);
   static void StoreVariable(Handle<Module> module, int cell_index,
                             Handle<Object> value);
@@ skipping 3560 matching lines @@
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #include "src/objects/object-macros-undef.h"
 
 #endif  // V8_OBJECTS_H_