Current UI tests are specific for windows. When installer supports Mac OS X there will be failures when UI tests are running on Mac. For example verification for Drive in selected path is valid only on Windows.

this.skip() call does not work for protractor tests, because it still considered as a failure. Second option would be do not run tests that are not valid for current platform at all. That could be done ether by direct check in tests like

if(process.platform === 'win32') {
  it('test desctription', function(){
    // test instructions
  });
}

or we can move platform specific tests in files with platform specific suffix and include them using process.platform and process.arch values at gulp execution time.