Index: src/wp-admin/js/common.js
===================================================================
--- src/wp-admin/js/common.js	(revision 41847)
+++ src/wp-admin/js/common.js	(working copy)
@@ -307,6 +307,7 @@
 		$sortables = $('.meta-box-sortables'),
 		wpResponsiveActive = false,
 		$adminbar = $( '#wpadminbar' ),
+		adminReadonlyTextarea = $( '.wp-admin textarea' ),
 		lastScrollPosition = 0,
 		pinnedMenuTop = false,
 		pinnedMenuBottom = false,
@@ -327,6 +328,21 @@
 		$(e.target).parent().siblings('a').get(0).click();
 	});
 
+	adminReadonlyTextarea.focus( function() {
+		var $this = $( this );
+
+		if ( $this.is( '[readonly]' ) ) {
+			$this.select();
+
+			// Work-around for Chrome's issue.
+			$this.mouseup( function() {
+				// Prevent further mouseup intervention.
+				$this.unbind( 'mouseup' );
+				return false;
+			});
+		}
+	});
+
 	$( '#collapse-button' ).on( 'click.collapse-menu', function() {
 		var viewportWidth = getViewportWidth() || 961;