Add unit tests for is_javascript_script_tag function #18

The html-api/auto-escape-javascript-json branch adds some new methods: is_javascript_script_tag and is_json_script_tag.

They're well documented referencing the HTML standard.

Create a PR against that branch to add unit tests for these two new methods.

The unit tests should be in a new test file and class:

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