[ES6 modules] Return previous error when an instantiation is reattempt.

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

Index: third_party/WebKit/Source/core/dom/ModulatorImpl.cpp
diff --git a/third_party/WebKit/Source/core/dom/ModulatorImpl.cpp b/third_party/WebKit/Source/core/dom/ModulatorImpl.cpp
index b41d3a4038568b5a5c0940a95339b1d9484e49ce..877b2265fd68f002ffd661bfa746e329c1ab8b10 100644
--- a/third_party/WebKit/Source/core/dom/ModulatorImpl.cpp
+++ b/third_party/WebKit/Source/core/dom/ModulatorImpl.cpp
@@ -128,6 +128,14 @@ ScriptValue ModulatorImpl::InstantiateModule(ScriptModule script_module) {
   return script_module.Instantiate(script_state_.Get());
 }
 
+ScriptValue ModulatorImpl::GetInstantiationError(
+    const ModuleScript* module_script) {
+  ScriptState::Scope scope(script_state_.Get());
+  return ScriptValue(
+      script_state_.Get(),
+      module_script->CreateInstantiationError(script_state_->GetIsolate()));
+}
+
 Vector<String> ModulatorImpl::ModuleRequestsFromScriptModule(
     ScriptModule script_module) {
   ScriptState::Scope scope(script_state_.Get());