Migrate 'iframed masonry block' tests to Playwright (#55016)

* Migrate 'iframed masonry block' tests to Playwright
* Remove old test files
* Use boundingBox

packages/e2e-tests/plugins/iframed-masonry-block.php

@@ -7,13 +7,6 @@
  * @package gutenberg-test-iframed-masonry-block
  */
 
-add_action(
-	'setup_theme',
-	static function () {
-		add_theme_support( 'block-templates' );
-	}
-);
-
 add_action(
 	'init',
 	static function () {

test/e2e/specs/editor/plugins/iframed-masonry-block.spec.js

@@ -0,0 +1,44 @@
+/**
+ * WordPress dependencies
+ */
+const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
+
+test.describe( 'iframed masonry block', () => {
+	test.beforeAll( async ( { requestUtils } ) => {
+		await requestUtils.activatePlugin(
+			'gutenberg-test-iframed-masonry-block'
+		);
+	} );
+
+	test.beforeEach( async ( { admin } ) => {
+		await admin.createNewPost();
+	} );
+
+	test.afterAll( async ( { requestUtils } ) => {
+		await requestUtils.deactivatePlugin(
+			'gutenberg-test-iframed-masonry-block'
+		);
+	} );
+
+	test( 'should load script and dependencies in iframe', async ( {
+		editor,
+	} ) => {
+		await editor.insertBlock( { name: 'test/iframed-masonry-block' } );
+
+		const masonry = editor.canvas.getByRole( 'document', {
+			name: 'Block: Iframed Masonry Block',
+		} );
+		await expect( masonry ).toBeVisible();
+
+		const masonryBox = await masonry.boundingBox();
+
+		// Expect Masonry to set a non-zero height.
+		expect( masonryBox.height ).toBeGreaterThan( 0 );
+
+		// Expect Masonry to absolute position items.
+		await expect( masonry.locator( '.grid-item' ).first() ).toHaveCSS(
+			'position',
+			'absolute'
+		);
+	} );
+} );