Merge branch '3135359-tests' into '3.0.x'

composer.json

...arkdown_test_no_parsers/markdown_test_no_parsers.info.yml

.../markdown_test_no_parsers/markdown_test_no_parsers.module

tests/src/Functional/FilterAdminTest.php

tests/src/Functional/MarkdownBrowserTestBase.php

tests/src/Functional/Plugin/Markdown/CommonMarkGfmTest.php

tests/src/Functional/Plugin/Markdown/CommonMarkTest.php

...src/Functional/Plugin/Markdown/MarkdownParserTestBase.php

tests/src/Functional/Plugin/Markdown/ParsedownExtraTest.php

tests/src/Functional/Plugin/Markdown/ParsedownTest.php

...s/src/Functional/Plugin/Markdown/PhpMarkdownExtraTest.php

tests/src/Functional/Plugin/Markdown/PhpMarkdownTest.php

tests/src/Kernel/Plugin/Markdown/CmarkTest.php

tests/src/Kernel/Plugin/Markdown/CommonMarkGfmTest.php

tests/src/Kernel/Plugin/Markdown/CommonMarkTest.php

tests/src/Kernel/Plugin/Markdown/MarkdownParserTestBase.php

tests/src/Kernel/Plugin/Markdown/ParsedownExtraTest.php

tests/src/Kernel/Plugin/Markdown/ParsedownTest.php

tests/src/Kernel/Plugin/Markdown/PhpMarkdownExtraTest.php

tests/src/Kernel/Plugin/Markdown/PhpMarkdownTest.php