File issues with HighlightJS

[alexeyinkin]

Some things in HighlightJS make the porting harder for us. We should file issues for them to simplify that because it will benefit their project as well as ours.

We should file them when we publish our package with all languages working so we can refer to it when justifying the changes for them. This will result in a higher chance for them to land. Until then accumulating these changes here:

• className: "" can be used instead of className: null for "explicit null" that overwrites other values.
• No TypeScript.
• Some languages do not have a name (TODO: list them here).