- Electron version: v1.3.3
- Operating system: OS X 10.11.6

v1.3.3 broke the detection of the `scroll-touch-begin` and `scroll-touch-end` events for me within a `webview`. It looks like the pull request #6754 caused this issue. v1.3.2 works as expected.

Behavior that I'm observing on v1.3.3:
- Most of the time, the `scroll-touch-*` events are not emitted when the cursor is on top of a `webview`.
- The `scroll-touch-*` events seem to be emitted _only once_ when the cursor is on a `webview` and on a scrollable element. The scrollable elements in my app have no native scrollbar set (they have the style `overflow: hidden;` set instead of `overflow: scroll;`). This is the case in which I need to receive the `scroll-touch-*` events.
- The `scroll-touch-*` events seem to work fine when the cursor is outside of the `webview` tag.

atom/browser/native_window.cc
extensions::SizeConstraints size_constraints;
  size_constraints.set_maximum_size(size);
  SetSizeConstraints(size_constraints);
}
gfx::Size NativeWindow::GetMaximumSize() {
  return GetSizeConstraints().GetMaximumSize();
}
void NativeWindow::SetSheetOffset(const double offsetX, const double offsetY) {
  sheet_offset_x_ = offsetX;
  sheet_offset_y_ = offsetY;
}
double NativeWindow::GetSheetOffsetX() {
  return sheet_offset_x_;
}
double NativeWindow::GetSheetOffsetY() {
  return sheet_offset_y_;
}
void NativeWindow::SetRepresentedFilename(const std::string& filename) {
}
std::string NativeWindow::GetRepresentedFilename() {
  return "";
}
void NativeWindow::SetDocumentEdited(bool edited) {
}
bool NativeWindow::IsDocumentEdited() {
  return false;
}
void NativeWindow::SetFocusable(bool focusable) {