RFR: 8337481: File API: file.name contains path instead of name

[Oliver Schmidtmer]

FileSystemJava had no valid implementation for pathFileName since the function was renamed from pathGetFileName to pathFileName in the FileSystem.h from WebKit

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Commit messages:
 - 8337481 Fix FileSystemJava.pathFileName

Changes: https://git.openjdk.org/jfx/pull/1551/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1551&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337481
  Stats: 13 lines in 2 files changed: 0 ins; 12 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1551.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1551/head:pull/1551

PR: https://git.openjdk.org/jfx/pull/1551