When quick actions are present in preview (render_quick_actions=true), source maps of everything after the quick action are incorrect

Summary

Rich text editor relies on render_quick_actions=true to show quick actions in editable comment so that people may modify it. However, including quick actions ruins the sourcemaps of everything that follows. This especially affects task lists which are one of the few elements that support sourcemaps.

List of elements that currently support sourcemaps: &7722

Steps to reproduce

Compare the output of the two different examples below:

1. With /assign:

/assign @himkp

test paragraph

Output HTML (incorrect):

<p data-sourcepos="2:1-2:14" dir="auto">/assign <a href="/himkp" data-reference-type="user" data-user="2398164" data-container="body" data-placement="top" class="gfm gfm-project_member js-user-link" title="Himanshu Kapoor">@himkp</a></p>&#x000A;<p data-sourcepos="5:1-5:12" dir="auto">test comment</p>

2. With /cc:

/cc @himkp

test paragraph

Output HTML (correct):

<p data-sourcepos="1:1-1:10" dir="auto">/cc <a href="/himkp" data-reference-type="user" data-user="2398164" data-container="body" data-placement="top" class="gfm gfm-project_member js-user-link" title="Himanshu Kapoor">@himkp</a></p>&#x000A;<p data-sourcepos="3:1-3:12" dir="auto">test comment</p>

What is the current bug behavior?

Line numbers are incorrect for every quick action (except `/cc`) and the content that follows it.

What is the expected correct behavior?

Line numbers should be the same as the output for /cc.