RFR: JDK-8228554: Accessibility errors in jdwp-protocol.html

[Alex Menkov]

Hi all,

Please review the fix for
https://bugs.openjdk.java.net/browse/JDK-8228554

webrev: 
http://cr.openjdk.java.net/~amenkov/jdk14/jdwp-protocol_accessibility/webrev/

generated docs:
old: 
http://cr.openjdk.java.net/~amenkov/jdk14/jdwp-protocol_accessibility/0/jdwp-protocol.html
new: 
http://cr.openjdk.java.net/~amenkov/jdk14/jdwp-protocol_accessibility/1/jdwp-protocol.html

specdiff:
http://cr.openjdk.java.net/~amenkov/jdk14/jdwp-protocol_accessibility/spectdiff/diff.html

Summary:
- "content outside of a region" issues:
   - <div role="banner"> replaced with with <header>,
   - <div role="main"> replaced with <main>;
- table issues:
   - added column headers to all tables;
   - for every row specified row header;
   - indentation with table "colspan" reimplemented by using CSS.

--alex