RFR: 8224922: Access JavaFileObject from Element(s) [v6]

[Joe Darcy]

> Initial review to get some comments on the shape of the API. Tests are needed of course, as well as some tuning of the spec to better describe differences in behavior when class files rather than source files are the backing file type.

Joe Darcy has updated the pull request incrementally with 10 additional commits since the last revision:

 - Merge pull request #3 from lahodaj/JDK-8224922
   
   Improvements to JDK-8224922
 - Test cleanup.
 - Cleanup.
 - Cleanup.
 - Merge remote-tracking branch 'darcy/JDK-8224922' into JDK-8224922
 - Attempting to fix tests.
 - Merge remote-tracking branch 'JDK-8224922' into JDK-8224922
 - Fixing behavior for nested classes
 - Attempting to improve Elements.getFileObjectOf
 - Merge branch 'master' into JDK-8224922

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5038/files
  - new: https://git.openjdk.java.net/jdk/pull/5038/files/d1b6fab1..1584c4b4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5038&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5038&range=04-05

  Stats: 344 lines in 5 files changed: 330 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5038.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5038/head:pull/5038

PR: https://git.openjdk.java.net/jdk/pull/5038