RFR: 8253117: Replace HTML tables in javadoc summaries with CSS grid elements [v4]

[Hannes Wallnöfer]

> This changes the output of the `html.markup.Table` class to plain `div` elements, using CSS Grid Layout to display them
> in a tabular format.
> I decided against renaming the Table class and related identifiers even though it does no longer emit an HTML <table>
> element. I admit this results in a somewhat odd mismatch in a few places, but on the other hand the generated HTML
> still represents tabular data. Also, the changes are much easier to understand and review this way. I'm open to
> renaming things if we can find a better terminology.  I simplified the existing code in quite a few places:
>  - Removed the setters for table tab ids and the browser tab script. The ids are now derived from the main table id which
>    makes them unique even with multiple tables per page (provided the tables have different ids), and the browser script
>    will always work for the used ids.
>  
>  - Removed the complex tab selection scheme based on bitwise operations and replaced it with one CSS class per tab. The
>    elements making up a table row will have a CSS class for each tab they belong to. The CSS class names are derived from
>    the table id as well.
> 
>  - Reduced per usage style classes for summary tables, thereby simplifying the style sheet. Instead of having a CSS class
>    for each useage of a table (e.g. `member-summary`, `type-summary` etc) there is only one common CSS class for summary
>    tables as well as one specifying the number of columns to use, e.g. `two-column-summary`, `three-column-summary` etc.
> 
> The rendering and spacing of the tables should be the same as previously. There are a few exceptions:
> 
>  - The style sheet has additional media queries to switch the layout of tables when the width of the browser window
>    becomes very narrow. This happens at different thresholds for tables with two, three, or four columns. Note that these
>    theresholds are based on heuristics, it is what I have found to work well under most circumstances.
> 
>  - The new grid never grow larger than the width available in the browser. When a table cell becomes too narrow to contain
>    its content, the cell becomes scrollable. This happens very rarely and is not too disturbing IMO.
> 
>  - Spacing of columns is usually a bit different than previously. Grids offers very complex layout options, and the
>    setting I came to use partitions space depending on the width of cell contents.
> 
> Here are the API docs for java.base rendered with these changes:
> http://cr.openjdk.java.net/~hannesw/8253117/api.00/
> 
> Here are the API docs with these changes and additionally the patch for JDK-8248566 (mobile browser optimizations)
> applied: http://cr.openjdk.java.net/~hannesw/8253117/api.00.mobile/

Hannes Wallnöfer has updated the pull request with a new target base due to a merge or a rebase. The pull request now
contains eight commits:

 - Merge master
 - Merge master
 - Address issues raised in code review:
    - remove unused styles and method
    - rename alternating table row styles
    - move id attribute for tabs
    - add line breaks in test text blocks to make them easier to read and maintain
 - Fix trailing whitespace
 - Clean up comments and styles
 - Restore table spacing
 - Adapt tests to grid summaries
 - Use CSS Grid Layout for javadoc summaries

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Changes: https://git.openjdk.java.net/jdk/pull/253/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=253&range=03
  Stats: 2540 lines in 61 files changed: 316 ins; 716 del; 1508 mod
  Patch: https://git.openjdk.java.net/jdk/pull/253.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/253/head:pull/253

PR: https://git.openjdk.java.net/jdk/pull/253