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

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

Index: third_party/WebKit/Source/core/dom/ModuleScript.h
diff --git a/third_party/WebKit/Source/core/dom/ModuleScript.h b/third_party/WebKit/Source/core/dom/ModuleScript.h
index 22002a40f486ad417cd4815badbe74b47791200e..feaf9025720d190e9228d03a96dd97f120d9d0d2 100644
--- a/third_party/WebKit/Source/core/dom/ModuleScript.h
+++ b/third_party/WebKit/Source/core/dom/ModuleScript.h
@@ -64,6 +64,10 @@ class CORE_EXPORT ModuleScript final : public Script, public TraceWrapperBase {
   // https://html.spec.whatwg.org/multipage/webappapis.html#internal-module-script-graph-fetching-procedure
   void SetInstantiationSuccess();
 
+  v8::Local<v8::Value> CreateInstantiationError(v8::Isolate* isolate) const {
+    return instantiation_error_.NewLocal(isolate);
+  }
+
   ParserDisposition ParserState() const { return parser_state_; }
   WebURLRequest::FetchCredentialsMode CredentialsMode() const {
     return credentials_mode_;