[jfx11u] RFR: 8209086: Some javafx.web files are missing GPLv2+Classpath copyright header

[Kevin Rushforth]

Clean backport of fix to add missing copyright headers. No changes other than comments.

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Commit messages:
 - 8209086: Some javafx.web files are missing GPLv2+Classpath copyright header

Changes: https://git.openjdk.java.net/jfx11u/pull/28/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=28&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8209086
  Stats: 591 lines in 27 files changed: 591 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx11u/pull/28.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/28/head:pull/28

PR: https://git.openjdk.java.net/jfx11u/pull/28