HTML API: Add support for HR element.

Adds support for the following HTML elements to the HTML Processor:

 - HR

Previously, this element was not supported and the HTML Processor would bail when encountering
it. Now, with this patch, it will proceed to parse an HTML document when encountering one.

Developed in WordPress#5897

Props jonsurrell, dmsnell
Fixes #60283



git-svn-id: https://develop.svn.wordpress.org/trunk@57314 602fd350-edb4-49c9-b593-d223f7449a82

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

@@ -109,7 +109,7 @@
  *  - Media elements: AUDIO, CANVAS, FIGCAPTION, FIGURE, IMG, MAP, PICTURE, VIDEO.
  *  - Paragraph: P.
  *  - Phrasing elements: ABBR, BDI, BDO, CITE, DATA, DEL, DFN, INS, MARK, OUTPUT, Q, SAMP, SUB, SUP, TIME, VAR.
- *  - Sectioning elements: ARTICLE, ASIDE, NAV, SECTION.
+ *  - Sectioning elements: ARTICLE, ASIDE, HR, NAV, SECTION.
  *  - Templating elements: SLOT.
  *  - Text decoration: RUBY.
  *  - Deprecated elements: ACRONYM, BLINK, CENTER, DIR, ISINDEX, MULTICOL, NEXTID, SPACER.
@@ -941,6 +941,17 @@ private function step_in_body() {
 				$this->reconstruct_active_formatting_elements();
 				$this->insert_html_element( $this->state->current_token );
 				return true;
+
+			/*
+			 * > A start tag whose tag name is "hr"
+			 */
+			case '+HR':
+				if ( $this->state->stack_of_open_elements->has_p_in_button_scope() ) {
+					$this->close_a_p_element();
+				}
+				$this->insert_html_element( $this->state->current_token );
+				$this->state->frameset_ok = false;
+				return true;
 		}
 
 		/*
@@ -977,7 +988,6 @@ private function step_in_body() {
 			case 'FRAME':
 			case 'FRAMESET':
 			case 'HEAD':
-			case 'HR':
 			case 'HTML':
 			case 'IFRAME':
 			case 'INPUT':

tests/phpunit/tests/html-api/wpHtmlProcessor.php

@@ -173,7 +173,6 @@ public function data_unsupported_special_in_body_tags() {
 			'FRAME'     => array( 'FRAME' ),
 			'FRAMESET'  => array( 'FRAMESET' ),
 			'HEAD'      => array( 'HEAD' ),
-			'HR'        => array( 'HR' ),
 			'HTML'      => array( 'HTML' ),
 			'IFRAME'    => array( 'IFRAME' ),
 			'INPUT'     => array( 'INPUT' ),

tests/phpunit/tests/html-api/wpHtmlProcessorBreadcrumbs.php

@@ -175,7 +175,6 @@ public function data_unsupported_elements() {
 			'FRAME',
 			'FRAMESET',
 			'HEAD',
-			'HR',
 			'HTML',
 			'IFRAME',
 			'INPUT',

tests/phpunit/tests/html-api/wpHtmlProcessorSemanticRules.php

@@ -224,6 +224,22 @@ public function test_in_body_button_with_button_in_scope_as_ancestor() {
 		$this->assertSame( array( 'HTML', 'BODY', 'BUTTON' ), $p->get_breadcrumbs(), 'Failed to produce expected DOM nesting for third button.' );
 	}
 
+	/**
+	 * Verifies that HR closes an open p tag
+	 *
+	 * @ticket 60283
+	 */
+	public function test_in_body_hr_element_closes_open_p_tag() {
+		$processor = WP_HTML_Processor::create_fragment( '<p><hr>' );
+
+		$processor->next_tag( 'HR' );
+		$this->assertSame(
+			array( 'HTML', 'BODY', 'HR' ),
+			$processor->get_breadcrumbs(),
+			'Expected HR to be a direct child of the BODY, having closed the open P element.'
+		);
+	}
+
 	/**
 	 * Verifies that H1 through H6 elements close an open P element.
 	 *