RFR: JDK-8287838: Update Float and Double to use snippets

[Joe Darcy]

Various code blocks in Float and Double would be better as snippets.

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Commit messages:
 - JDK-8287838: Update Float and Double to use snippets

Changes: https://git.openjdk.java.net/jdk/pull/9034/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9034&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287838
  Stats: 6 lines in 2 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/9034.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/9034/head:pull/9034

PR: https://git.openjdk.java.net/jdk/pull/9034