Function getRecordWithOldValue

test/polyfills/MutationObserver.js:204–209

(oldValue)

    return currentRecord = new MutationRecord(type, target);
  }
  function getRecordWithOldValue(oldValue) {
    if (recordWithOldValue) return recordWithOldValue;
    recordWithOldValue = copyMutationRecord(currentRecord);
    recordWithOldValue.oldValue = oldValue;
    return recordWithOldValue;
  }
  function clearRecords() {
    currentRecord = recordWithOldValue = undefined;
  }