Login: Revert selector change in login heading CSS.

In [59138], the login screens were updated to change the `h1` heading from the logo to screen-reader hidden text. Along with that HTML change, we changed the CSS selectors from `.login h1` to `.login .wp-login-logo`. This unnecessary change increased specificity and broke the CSS selectors used by a wide variety of plugins to replace the login logo.

Commit reverts the change in selector back to using the `.login h1` pattern.

Props leecollings, sabernhardt, im3dabasia1, roytanck, sailpete, joedolson. 
Fixes #62410.

git-svn-id: https://develop.svn.wordpress.org/trunk@59424 602fd350-edb4-49c9-b593-d223f7449a82

Author: joedolson

src/wp-admin/css/login.css

@@ -269,11 +269,11 @@ p {
 	vertical-align: baseline;
 }
 
-.login .wp-login-logo {
+.login h1 {
 	text-align: center;
 }
 
-.login .wp-login-logo a {
+.login h1 a {
 	background-image: url(../images/w-logo-blue.png?ver=20131202);
 	background-image: none, url(../images/wordpress-logo.svg?ver=20131107);
 	background-size: 84px;
@@ -323,13 +323,13 @@ p {
 
 .login #nav a:hover,
 .login #backtoblog a:hover,
-.login .wp-login-logo a:hover {
+.login h1 a:hover {
 	color: #135e96;
 }
 
 .login #nav a:focus,
 .login #backtoblog a:focus,
-.login .wp-login-logo a:focus {
+.login h1 a:focus {
 	color: #043959;
 }
 
@@ -390,7 +390,7 @@ body.interim-login {
 	margin: 5px auto 20px;
 }
 
-.interim-login.login .wp-login-logo a {
+.interim-login.login h1 a {
 	width: auto;
 }