Introduce a new, cross-browser HiDPI CSS @media rule to be used everywhere.

{{{
@media print,
  (-o-min-device-pixel-ratio: 5/4),
  (-webkit-min-device-pixel-ratio: 1.25),
  (min-resolution: 120dpi) {
}}}

Serve HiDPI graphics for printing, regardless of screen resolution.

Specify Opera's vendor-prefixed device pixel ratio property, for Opera desktop.

Specify a minimum Webkit device pixel ratio of 1.25 instead of 1.5, to serve
2x images to Android devices that are between 1 and 1.5x (like the Nexus 7).
Firefox and Opera will respond to 1.5x on these devices, but Chrome will not.

Specify min-resolution, which covers Firefox 19. Opera on Android also supports
min-resolution, but Opera Mini does not support dppx, so the dpi unit is used.

props iammattthomas for the exhaustive research.
props lessbloat for patching.

fixes #22238.



git-svn-id: http://core.svn.wordpress.org/trunk@22629 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/install.css

@@ -74,7 +74,10 @@ abbr {
 	overflow: hidden;
 	display: block;
 }
-@media only screen and (-webkit-min-device-pixel-ratio: 1.5) {
+@media print,
+  (-o-min-device-pixel-ratio: 5/4),
+  (-webkit-min-device-pixel-ratio: 1.25),
+  (min-resolution: 120dpi) {
 	#logo a {
 		background-image: url('../images/wordpress-logo-2x.png?ver=20120412');
 		background-size: 274px 63px;