RFR: 7062: Update to the Eclipse 2020-12 platform

[Marcus Hirt]

Also updating the babel bundles for the 2020-09 platform.

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Commit messages:
 - 7062: Updating platform to 2020-12

Changes: https://git.openjdk.java.net/jmc/pull/185/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=185&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7062
  Stats: 36 lines in 6 files changed: 21 ins; 0 del; 15 mod
  Patch: https://git.openjdk.java.net/jmc/pull/185.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/185/head:pull/185

PR: https://git.openjdk.java.net/jmc/pull/185