RFR: 8247957: remove doclint support for HTML 4 [v2]

[Magnus Ihse Bursie]

On Tue, 15 Dec 2020 07:26:15 GMT, Yoshiki Sato <ysatowse at openjdk.org> wrote:

>> HTML4 is no longer supported in javadoc.
>> 
>> doclint needs to drop HTML4 support as well.
>> The changes consist of:
>> * Removing jdk.javadoc.internal.doclint.HtmlVersion and its references.
>> * Sorting out supported tags and attributes in HTML5 (including fix incorrect permission of valign in TH, TR, TD, THEAD and TBODY)
>> * Modifying test code and expected outputs to be checked in HTML5
>
> Yoshiki Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8257204 and 8256313
>   8257204: Remove usage of -Xhtmlversion option from javac
>   8256313: JavaCompilation.gmk needs to be updated not to use --doclint-format html5 option

Build change look fine. I have not looked at the other changes.

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Marked as reviewed by ihse (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/893