Format comments which have no end comments should not generate end comments

[clembo590]

vscode Version: 1.50.1
on macosx version 10.14.6

There is an error when performing "format modified lines": please see following gif to get the scenario.

[angelozerr]

Thanks for reporting this issue.

This problem is easy to reproduce.

Given this XML:

<foo>
	<!-- 
</foo>

After formatting, it generates the end comment:

<foo>
	<!-- 
</foo>-->

Although it should not generate the -->.

There is the same problem with CDATA:

<foo>
	<![CDATA[ 
</foo>

This problem should be fixed with the PR eclipse-lemminx/lemminx#920