[ES6 modules] Rethrow instantiation error when attempt to resolve instantiation failed module.

third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.cpp

 // Copyright 2017 The Chromium 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 "core/dom/ScriptModuleResolverImpl.h"
 
 #include "bindings/core/v8/ScriptModule.h"
 #include "core/dom/Modulator.h"
 #include "core/dom/ModuleScript.h"
 
@@ skipping 50 matching lines @@
     exception_state.ThrowTypeError(
         "Failed to load module script for module specifier '" + specifier +
         "'");
     return ScriptModule();
   }
 
   // Step 5. If resolved module script's instantiation state is "errored", then
   // throw resolved module script's instantiation error.
   if (module_script->InstantiationState() ==
       ModuleInstantiationState::kErrored) {
-    // TODO(kouhei): Implement this path once
-    // https://codereview.chromium.org/2782403002/ landed.
-    NOTIMPLEMENTED();
+    ScriptValue error = modulator_->GetInstantiationError(module_script);
+    exception_state.RethrowV8Exception(error.V8Value());
     return ScriptModule();
   }
 
   // Step 6. Assert: resolved module script's instantiation state is
   // "instantiated" (and thus its module record is not null).
-  // TODO(kouhei): Enable below check once once
-  // https://codereview.chromium.org/2782403002/ landed.
-  // CHECK_EQ(moduleScript->instantiationState(),
-  // ModuleInstantiationState::Instantiated);
+  CHECK_EQ(module_script->InstantiationState(),
+           ModuleInstantiationState::kInstantiated);
+  ScriptModule record = module_script->Record();
+  CHECK(!record.IsNull());
 
   // Step 7. Return resolved module script's module record.
-  return module_script->Record();
+  return record;
 }
 
 DEFINE_TRACE(ScriptModuleResolverImpl) {
   ScriptModuleResolver::Trace(visitor);
   visitor->Trace(record_to_module_script_map_);
   visitor->Trace(modulator_);
 }
 
 }  // namespace blink