Accessibility: Insert Link modal: Improve keyboard interaction.

Avoids change the selected link when using the Shift + Up/Down arrow keys
to select text in the form fields.

Props afercia.

Merges [42807] to the 5.0 branch.
Fixes #43253.
Built from https://develop.svn.wordpress.org/branches/5.0@44405


git-svn-id: http://core.svn.wordpress.org/branches/5.0@44235 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/wplink.js

@@ -559,7 +559,7 @@ var wpLink;
 			}
 
 			// Up Arrow and Down Arrow keys.
-			if ( 38 !== event.keyCode && 40 !== event.keyCode ) {
+			if ( event.shiftKey || ( 38 !== event.keyCode && 40 !== event.keyCode ) ) {
 				return;
 			}
 

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.0.3-alpha-44404';
+$wp_version = '5.0.3-alpha-44405';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.