Revert "Dartium JS Interop enabled."

tools/dom/templates/html/impl/impl_ServiceWorker.darttemplate

Index: tools/dom/templates/html/impl/impl_ServiceWorker.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_ServiceWorker.darttemplate b/tools/dom/templates/html/impl/impl_ServiceWorker.darttemplate
deleted file mode 100644
index 6cb64ab3ad1ad928fd763f04f48b6a51ba93373b..0000000000000000000000000000000000000000
--- a/tools/dom/templates/html/impl/impl_ServiceWorker.darttemplate
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of $LIBRARYNAME;
-
-@DocsEditable()
-$(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
-$!MEMBERS
-$if DARTIUM
-  // Override these methods for Dartium _ServiceWorker can't be abstract.
-  Stream<ErrorEvent> get onError => errorEvent.forTarget(this);
-$endif
-}
-