[7u6] Please review my fix for 7124247: [macosx] Implement GraphicsDevice.setDisplayMode()

[Alexander Zuev]

Hello,

   slightly updated fix for CR 7124247: [macosx] Implement 
GraphicsDevice.setDisplayMode()

   Actually it is a backport to the 7u6 of the fix for jdk8 with minor 
corrections - fixed situation with the getDisplayModes() when we 
returned the wrong resolutions for the requested modes, fixed crash when 
we repeatedly asked to set display mode in a quick sentence and now 
setDisplayMode correctly throws an IllegalArgumentException instead of 
NullPointerException if null is passed as a parameter.

   CR description can be found here: 
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7124247

   Webrev with the proposed change can be seen here: 
http://cr.openjdk.java.net/~kizune/7124247/jdk7u6/webrev.02

With best regards,
Alex