实现
Entry getAsEntry() {
Entry entry = _webkitGetAsEntry() as Entry;
if (entry.isFile!) {
applyExtension('FileEntry', entry);
applyExtension('webkitFileSystemFileEntry', entry);
applyExtension('FileSystemFileEntry', entry);
} else if (entry.isDirectory!) {
applyExtension('DirectoryEntry', entry);
applyExtension('webkitFileSystemDirectoryEntry', entry);
applyExtension('FileSystemDirectoryEntry', entry);
} else {
applyExtension('Entry', entry);
applyExtension('webkitFileSystemEntry', entry);
applyExtension('FileSystemEntry', entry);
}
return entry;
}