[ES6 modules] ModuleTreeLinker::Instantiate shouldn't proceed on invalid context

third_party/WebKit/Source/core/testing/DummyModulator.cpp

Index: third_party/WebKit/Source/core/testing/DummyModulator.cpp
diff --git a/third_party/WebKit/Source/core/testing/DummyModulator.cpp b/third_party/WebKit/Source/core/testing/DummyModulator.cpp
index e5dcd6994e659b00dd9b73001bda9ba385696fac..d8a1e865a56cd07d0c6da67c1e9debb644d3ca42 100644
--- a/third_party/WebKit/Source/core/testing/DummyModulator.cpp
+++ b/third_party/WebKit/Source/core/testing/DummyModulator.cpp
@@ -91,6 +91,10 @@ void DummyModulator::FetchNewSingleModule(const ModuleScriptFetchRequest&,
   NOTREACHED();
 }
 
+bool DummyModulator::HasValidContext() {
+  return true;
+}
+
 ScriptModule DummyModulator::CompileModule(const String& script,
                                            const String& url_str,
                                            AccessControlStatus) {