Customize: Prevent outputting `value` attribute if already supplied among `input_attrs`.

This allows for `input[type=button]` controls to be added without producing illegal HTML.

Amends [41740].
See #30738, #33085.

Built from https://develop.svn.wordpress.org/trunk@41822


git-svn-id: http://core.svn.wordpress.org/trunk@41656 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-control.php

@@ -649,7 +649,9 @@ class WP_Customize_Control {
 					type="<?php echo esc_attr( $this->type ); ?>"
 					<?php echo $describedby_attr; ?>
 					<?php $this->input_attrs(); ?>
-					value="<?php echo esc_attr( $this->value() ); ?>"
+					<?php if ( ! isset( $this->input_attrs['value'] ) ) : ?>
+						value="<?php echo esc_attr( $this->value() ); ?>"
+					<?php endif; ?>
 					<?php $this->link(); ?>
 					/>
 				<?php

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-beta1-41821';
+$wp_version = '4.9-beta1-41822';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.