Themes: Remove a Chrome workaround that causes theme screenshots to look too crisp and no longer appears to be relevant.

props mzak.
fixes #26584.

git-svn-id: https://develop.svn.wordpress.org/trunk@31316 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/themes.css

@@ -153,8 +153,7 @@
 	left: 0;
 	top: 0;
 	width: 100%;
-	-webkit-transform: translateZ( 0 ); /* Prevents rendering bugs in Chrome */
-	-webkit-transition: opacity 0.2s ease-in-out; /* Prevents rendering bugs in Chrome */
+	-webkit-transition: opacity 0.2s ease-in-out;
 	transition: opacity 0.2s ease-in-out;
 }