IndexedDB: Align abort behavior on uncaught exception with Gecko

third_party/WebKit/LayoutTests/external/wpt/IndexedDB/support.js

 var databaseName = "database";
 var databaseVersion = 1;
 
 /* Delete created databases
  *
  * Go through each finished test, see if it has an associated database. Close
  * that and delete the database. */
 add_completion_callback(function(tests)
 {
     for (var i in tests)
@@ skipping 125 matching lines @@
 function expect(t, expected) {
   var results = [];
   return result => {
     results.push(result);
     if (results.length === expected.length) {
       assert_array_equals(results, expected);
       t.done();
     }
   };
 }
+
+// Checks to see if the passed transaction is active (by making
+// requests against the named store).
+function is_transaction_active(tx, store_name) {
+  try {
+    const request = tx.objectStore(store_name).get(0);
+    request.onerror = e => {
+      e.preventDefault();
+      e.stopPropagation();
+    };
+    return true;
+  } catch (ex) {
+    assert_equals(ex.name, 'TransactionInactiveError',
+                  'Active check should either not throw anything, or throw ' +
+                  'TransactionInactiveError');
+    return false;
+  }
+}