Login and Registration: Restore underline on links.

Increase recognizability of links on the login and registration screens by removing the `text-decoration:none` attribute. Move text decoration position to 'under' for better visibility and relationship with arrows.

Props dcavins, khushdoms, audrasjb, khokansandar, sabernhardt, afercia, joedolson.
Fixes #65075.

git-svn-id: https://develop.svn.wordpress.org/trunk@62597 602fd350-edb4-49c9-b593-d223f7449a82

Author: joedolson

src/wp-admin/css/login.css

@@ -19,6 +19,7 @@ a {
 	transition-property: border, background, color;
 	transition-duration: .05s;
 	transition-timing-function: ease-in-out;
+	text-underline-position: under;
 }
 
 a {
@@ -326,7 +327,6 @@ p {
 
 .login #nav a,
 .login #backtoblog a {
-	text-decoration: none;
 	color: #50575e;
 }