RFR: 8235670: Javadoc pages not printing correctly in some browsers

[Hannes Wallnöfer]

Please review: 

JBS: https://bugs.openjdk.java.net/browse/JDK-8235670
Webrev: http://cr.openjdk.java.net/~hannesw/8235670/webrev.00/
API docs: http://cr.openjdk.java.net/~hannesw/8235670/api.00/

Pavel discovered today that Javadoc pages with the CSS Flexbox layout don’t print correctly on browsers such as Safari or Firefox. Fortunately, this can be fixed quite easily by limiting the flexbox layout to the „screen" @media type, leaving „print“ and „speech“ @media types with the plain layout. 

I have also added a directive to hide the navigation links and search box in the „print“ layout, which helps to remove some useless clutter from printed documentation.

Thanks,
Hannes