RFR: 8247957: remove doclint support for HTML 4 [v7]

[Jonathan Gibbons]

On Fri, 25 Dec 2020 02:17:16 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 -Xhtmlversion option from doclint and --doclint-format from javac.
>> * Removing jdk.javadoc.internal.doclint.HtmlVersion and its references.
>> * Updating makefile not to use removed option.
>> * Sorting out supported tags and attributes in HTML5 (including fix incorrect permission of valign in TH, TR, TD, THEAD and TBODY)
>> * Fixing incorrect value checks for the id attribute.
>> * Modifying test code and expected outputs to be checked in HTML5
>
> Yoshiki Sato has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:
> 
>  - Merge master
>  - 7th: Some fixes and additional changes for 8247957
>  - 5th: 8258460: Remove --doclint-format option from javac
>  - 5th: 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
>  - 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
>  - 3rd: 8247957 and 8256312
>  - Merge branch 'master' into JDK-8247957_2
>  - 8247957: remove doclint support for HTML 4
>    8256312: Valid anchor 'id' value not allowed
>  - 8247957: remove doclint support for HTML 4

Marked as reviewed by jjg (Reviewer).

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