Fix return type in SectionListener

[thewilkybarkid]

Not currently visible in tests as

browser/vendor-extra/LiberoPageBundle/tests/ViewConvertingTestCase.php

Lines 17 to 27 in 5bfb50b

	final protected function createDumpingConverter() : ViewConverter
	{
	return new CallbackViewConverter(
	function (NonDocumentTypeChildNode $node, ?string $template = null, array $context = []) : View {
	return new TemplateView(
	null,
	['node' => $node->getNodePath(), 'template' => $template, 'context' => $context]
	);
	}
	);
	}

returns a TemplateView. Makes me think we need a specialist type there.

[giorgiosironi]

createDumpingConverter could specify a stricter type in the anonymous function it uses, but currently it specifies an interface (View) rather than a concrete class instead which is a good thing. Little difference.

[thewilkybarkid]

Similar to #68 and #64 (comment); might better to allow the tests to compare a normalized (JSON-like) form. So ViewConvertingTestCase::createDumpingConverter() would return a special (anonymous?) View implementation and requires using dump() to check it. (JSON-like so is similar to how Twig will read it.)

(Or reintroduce JsonSerializable.)

[giorgiosironi]

https://github.com/libero/browser/blob/master/vendor-extra/ViewsBundle/src/Views/CallbackViewConverter.php#L19 returns View so this matches that.