This is done by setting the ‘disableJavaScriptAPI’ key to ‘true’ in the tmCommand file.
The rationale behind this is that a command like “HTML → Show Preview” is using the HTML output view with user data which should not have access to the special TextMate JavaScript object, for example a user may have a `<script>` tag that loads JavaScript from a CDN, and such script would effectively have shell access to the user’s machine.
The previous name was inspired by WebView’s default API but it sounds like it is just the default implementation with a default baseURL: parameter, hence why I prefer to name it something different.