Allow WebKit browsers to break strings in <code> tags.

This prevents an overflow for example on Permalink Settings.

fixes #28161.

git-svn-id: https://develop.svn.wordpress.org/trunk@29501 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/common.css

@@ -3055,6 +3055,10 @@ img {
 		right: -190px;
 	}
 
+	code {
+		word-wrap: break-word;
+	}
+
 	/* General Metabox */
 	.postbox {
 		font-size: 14px;