WebInstaller inline documentation cleanup

This is a follow-up to Ide17d5af13c416c62a40029848ac17ba24eb5563.
However, I could not fix the "minor style" issue mentioned there
because this would make the line to long.

I fixed lots and lots of other issues instead, e.g.:

* "void" isn't a thing. Added "return null" instead.
* Removed documentation that said "a constructor is a constructor".
* Use "string[]" and such instead of "array" if possible.

Change-Id: I9658c2af58862f1d634cf1b2ba4c9d0f27ee7608
Merge "WebInstaller inline documentation cleanup"