Keyboard.Key#onReleased() should handle inside parameter.

The boolean parameter of Keyboard.Key#onReleased(boolean) has
been somehow ignored since Capcake.  With this CL, that method
starts working as documented.

Alternatively we could fix the issue when and only when the
application's targetSdkVersion >= 23.  We didn't do that because:
- Although Keyboard.Key class is a public API, it is supposed to
  be used almost only by android.inputmethodservice.KeyboardView.
  The risk of unwanted compatibility problems is low.
- Fixing that is beneficial for users because it actually fixes
  UX issue when applications/IMEs that still rely on KeyboardView
  run in Android M.
- All the fields that are related to Keyboard.Key#onReleased are
  public fields so developers can easily work around anyway.

Bug: 21446448
Change-Id: I392166c77cd9dd2c432dc4f1274312f8355de02b