Quick fix to placate checked mode.

tests/dom/indexeddb_4_test.dart

 #library('IndexedDB4Test');
 #import('../../lib/unittest/unittest.dart');
 #import('../../lib/unittest/dom_config.dart');
 #import('dart:dom');
 
 // Test for IDBKeyRange and IDBCursor.
 
 final String DB_NAME = 'Test';
 final String STORE_NAME = 'TEST';
 final String VERSION = '1';
@@ skipping 41 matching lines @@
   fail(message) => (e) {
     callbackDone();
     Expect.fail('IndexedDB failure: $message');
   };
 
   testRange(range, expectedFirst, expectedLast) {
     IDBTransaction txn = db.transaction(STORE_NAME, IDBTransaction.READ_ONLY);
     IDBObjectStore objectStore = txn.objectStore(STORE_NAME);
     IDBRequest cursorRequest = objectStore.openCursor(range);
     int itemCount = 0;
-    int firstKey = null;
-    int lastKey = null;
+    num firstKey = null;
+    num lastKey = null;
     cursorRequest.addEventListener("success", (e) {
         var cursor = e.target.result;
         if (cursor != null) {
           if (firstKey == null) firstKey = cursor.key;
           lastKey = cursor.key;
           itemCount += 1;
           Expect.equals('Item ${cursor.key.toStringAsFixed(0)}', cursor.value);
           cursor.continueFunction();
         } else {
           // Done
@@ skipping 58 matching lines @@
   asyncTest('upper2', 1, test.upper2);
   asyncTest('upper3', 1, test.upper3);
 
   asyncTest('bound1', 1, test.bound1);
   asyncTest('bound2', 1, test.bound2);
   asyncTest('bound3', 1, test.bound3);
   asyncTest('bound4', 1, test.bound4);
   asyncTest('bound5', 1, test.bound5);
 
 }