* Electron version: 1.6.0
* Operating system: MacOS 10.12.2

### Expected behavior

'scroll-touch-end' emits when trackpad scrolling ends.

### Actual behavior

The begin event emits, but not the end

### How to reproduce

Example repo: https://github.com/pfrazee/electron-bug-no-scroll-touch-end

atom/browser/native_window.cc
web_contents()->GetRenderViewHost()->GetWidget()->Blur();
}
bool NativeWindow::IsWebViewFocused() {
  auto host_view = web_contents()->GetRenderViewHost()->GetWidget()->GetView();
  return host_view && host_view->HasFocus();
}
void NativeWindow::SetAutoHideMenuBar(bool auto_hide) {
}
bool NativeWindow::IsMenuBarAutoHide() {
  return false;
}
void NativeWindow::SetMenuBarVisibility(bool visible) {
}
bool NativeWindow::IsMenuBarVisible() {
  return true;
}
double NativeWindow::GetAspectRatio() {
  return aspect_ratio_;
}
gfx::Size NativeWindow::GetAspectRatioExtraSize() {
  return aspect_ratio_extraSize_;
}
void NativeWindow::SetAspectRatio(double aspect_ratio,
                                  const gfx::Size& extra_size) {
  aspect_ratio_ = aspect_ratio;
  aspect_ratio_extraSize_ = extra_size;
}
void NativeWindow::PreviewFile(const std::string& path,