message: Use default modifier state
  The tests were using a manually setup `ModifiersState`, to clean things
  up a bit the `ModifiersState::default` method has been used to replace
  this.
diff: @@ -741,12 +741,7 @@ mod tests {
  state: ElementState::Pressed,
  button: MouseButton::Left,
  device_id: unsafe { ::std::mem::transmute_copy(&0) },
  - modifiers: ModifiersState {
  - shift: false,
  - ctrl: false,
  - alt: false,
  - logo: false,
  - },
  + modifiers: ModifiersState::default(),
  },
  window_id: unsafe { ::std::mem::transmute_copy(&0) },
  },
  @@ -762,12 +757,7 @@ mod tests {
  state: ElementState::Pressed,
  button: MouseButton::Left,
  device_id: unsafe { ::std::mem::transmute_copy(&0) },
  - modifiers: ModifiersState {
  - shift: false,
  - ctrl: false,
  - alt: false,
  - logo: false,
  - },
  + modifiers: ModifiersState::default(),
  },
  window_id: unsafe { ::std::mem::transmute_copy(&0) },
  },
  @@ -783,12 +773,7 @@ mod tests {
  state: ElementState::Pressed,
  button: MouseButton::Left,
  device_id: unsafe { ::std::mem::transmute_copy(&0) },
  - modifiers: ModifiersState {
  - shift: false,
  - ctrl: false,
  - alt: false,
  - logo: false,
  - },
  + modifiers: ModifiersState::default(),
  },
  window_id: unsafe { ::std::mem::transmute_copy(&0) },
  },
  