Remove =List in JS, use JSExtendableArray instead.

tools/dom/templates/html/dart2js/indexed_db_dart2js.darttemplate

Index: tools/dom/templates/html/dart2js/indexed_db_dart2js.darttemplate
===================================================================
--- tools/dom/templates/html/dart2js/indexed_db_dart2js.darttemplate	(revision 24309)
+++ tools/dom/templates/html/dart2js/indexed_db_dart2js.darttemplate	(working copy)
@@ -14,6 +14,7 @@
 import 'dart:typed_data';
 import 'dart:_js_helper' show Creates, Returns, JSName, Null;
 import 'dart:_foreign_helper' show JS;
+import 'dart:_interceptors' show JSExtendableArray;
 
 $!GENERATED_DART_FILES
 
@@ -127,7 +128,7 @@
   return convertNativeToDart_AcceptStructuredClone(object, mustCopy: false);
 }
 
-
-const String _idbKey = '=List|=Object|num|String';  // TODO(sra): Add DateTime.
+// TODO(sra): Add DateTime.
+const String _idbKey = 'JSExtendableArray|=Object|num|String';
 const _annotation_Creates_IDBKey = const Creates(_idbKey);
 const _annotation_Returns_IDBKey = const Returns(_idbKey);