HTML API: Add missing NOBR end tag handling to HTML Processor.

When the HTML Processor was introduced, an oversight led to a missing case for handling a closing `NOBR` tag. The `NOBR` element is a deprecated tag and should not be used.

This patch adds the missing case so that the deprecated `NOBR` end tag is appropriately handled.

Developed in #7282
Discussed in https://core.trac.wordpress.org/ticket/61576

Follow-up to [56274].

Props jonsurrell.
See #61576.


git-svn-id: https://develop.svn.wordpress.org/trunk@58967 602fd350-edb4-49c9-b593-d223f7449a82

Author: dmsnell

src/wp-includes/html-api/class-wp-html-processor.php

@@ -2415,6 +2415,7 @@ private function step_in_body(): bool {
 			case '-EM':
 			case '-FONT':
 			case '-I':
+			case '-NOBR':
 			case '-S':
 			case '-SMALL':
 			case '-STRIKE':