Fallback to word highlighting when contributions don't provide document highlights

[bgashler1]

• VSCode Version: Insiders
• OS Version: Windows 10

Regarding test plan item #12100

Steps to Reproduce:

1. May not be a problem, but just filing this issue to be safe. I'm looking at an old version of VS Code site that was originally written in Razor. It's the example-word-count.cshtml file https://github.com/Microsoft/vscode-website/tree/3cfa8213681f680418997c7671fa1b8c452ac2af
2. Try clicking on the class name updateWordCount pictured below on line 79 and note that it doesn't match the symbol with a highlight like it does in Stable today as shown in the picture.

Left is Insiders. Right is Stable.

[dbaeumer]

Word highlight is broken in CSHTML. Not sure if this should be the normal word highlight or whether this is a language word highlighter.

[sandy081]

I see word highlighting is broken for HTML, CSHTML and HandleBars

Since, HTML has been extracted into a separate language server and this functionality has been lost. Moving to October.

This has to be documented as limitation in release notes

[felixfbecker]

#1751?

[aeschli]

The html extension registers a document highlighter provider. This seems to prevent the default word highlighting. The same seems to happen in TypeScript: Select a word in a comment does not highlight it. Handing over to @jrieken.