* Electron version: 1.4.15 (probably older versions too).
* Operating system: macOS 10.12.2

When Quick Look is launched by right-clicking a file in a file dialog, clicking its close button doesn't work (and there's an audible beep), and after enough clicking around frequently it crashes. I suspect the same thing would happen using `dialog.showOpenDialog` presented as a sheet, but I haven't tested.

Minimal app to reproduce:
```js
const {app, BrowserWindow} = require('electron')

app.on('ready', () => {
  const win = new BrowserWindow({width: 300, height: 100})
  win.loadURL('data:text/html,<input type="file">')
})
```

Example:
![quicklook](https://cloud.githubusercontent.com/assets/5355/22160125/06120964-df12-11e6-86db-996f2233bf5e.gif)

Crash log: https://gist.github.com/javan/4c19dddd73b0581e60f6baf3b75d4dd8
atom/browser/web_dialog_helper.cc
: window_(window),
      weak_factory_(this) {
}
WebDialogHelper::~WebDialogHelper() {
}
void WebDialogHelper::RunFileChooser(
    content::RenderFrameHost* render_frame_host,
    const content::FileChooserParams& params) {
  std::vector<content::FileChooserFileInfo> result;
  file_dialog::DialogSettings settings;
  settings.filters = GetFileTypesFromAcceptType(params.accept_types);
  settings.parent_window = window_;
  settings.title = base::UTF16ToUTF8(params.title);
  if (params.mode == content::FileChooserParams::Save) {
    base::FilePath path;
    settings.default_path = params.default_file_name;
    if (file_dialog::ShowSaveDialog(settings, &path)) {
      content::FileChooserFileInfo info;
      info.file_path = path;
      info.display_name = path.BaseName().value();
      result.push_back(info);
    }
  } else {
    int flags = file_dialog::FILE_DIALOG_CREATE_DIRECTORY;
    switch (params.mode) {
      case content::FileChooserParams::OpenMultiple:
        flags |= file_dialog::FILE_DIALOG_MULTI_SELECTIONS;
      case content::FileChooserParams::Open: