RFR: 8205137: Remove Applet support from SwingSet2

[Alisen Chung]

removed support for running demo from applet for J2Ddemo and SwingSet2
same PR as 8205137: Remove Applet support from SwingSet2 #5400 (changed branch name)

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Commit messages:
 - 8205137: Remove Applet support from SwingSet2
 - 8205139: Remove Applet support from J2Ddemo

Changes: https://git.openjdk.java.net/jdk/pull/5401/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5401&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8205137
  Stats: 61 lines in 19 files changed: 0 ins; 39 del; 22 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5401.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5401/head:pull/5401

PR: https://git.openjdk.java.net/jdk/pull/5401