RFR: JDK-8248320: Provide a unique accessible name for <nav role="navigation"> [v2]

[Hannes Wallnöfer]

On Fri, 23 Oct 2020 15:23:50 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

>> This change is primarily about removing the lower (bottom) instance of the navigation bar, but as a side effect, it is also a cleanup for the way that the `<header>` and `<footer>` elements are generated for each page.
>> 
>> The header and footer elements are now generated by two new methods on `HtmlDocletWriter`: `getHeader` and `getFooter`. 
>> 
>> The footer is the same for all pages, and now just consists of the "bottom" text (if any) provided with the `-bottom` option. (In JDK API docs, this is all the legal text at the bottom of each page.)  The footer is omitted if there is no bottom text. 
>> 
>> The header is structurally the same for each page, consisting of the "top" text (if any) provided with the `-top` option, and the main navigation bar. The contents of the navigation bar does depend on the kind of page, and so it is generated by a new method `getNavBar`, which is overridden as needed for some pages, to properly customize the properties.
>> 
>> Since there is no longer a lower navbar, the `-footer` option, which could be used to inject user-provided text into the bar bar, is now redundant. For now, it is accepted but generates a warning if used.
>
> Jonathan Gibbons has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:
> 
>  - Merge master
>  - introduce getHeader
>  - JDK-8248320: Provide a unique accessible name for <nav role="navigation">

Looks good, Jon!

In order to clean up, the following could and should probably be removed:
 - `HtmlStyle.bottomNav`
 - Instances of `bottom-nav` in stylesheet.css
 - `*_BOTTOM_NAVBAR` constants in MarkerComments

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Marked as reviewed by hannesw (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/710