Updated to Drupal 8.6.4, which is PHP 7.3 friendly. Also updated HTMLaw library....

[yaffs-website] / web / core / modules / system / tests / themes / test_subsubtheme / test_subsubtheme.info.yml

name: 'Theme test subsubtheme'
type: theme
description: 'Test theme which uses test_subtheme as the base theme.'
version: VERSION
core: 8.x
base theme: test_subtheme