dart2wasm: Fix previously missed cases of "unintended" HTML in comments

Work towards https://github.com/dart-lang/sdk/issues/64155

(Mostly dart format changes until you get to the end)


The first line of these lines is only indented _3_ columns from the paragraph text; it must be indented 4.

Change-Id: Ib219eb73aea15be86428bda6b4bfae4565ea6678
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/544441
Commit-Queue: Stephen Adams <sra@google.com>
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Stephen Adams <sra@google.com>