RFR: 8339168: Optimize ClassFile Util slotSize [v2]

[Shaojin Wen]

> A small optimization to improve the performance of jdk.internal.classfile.impl.Util#slotSize/isDoubleSlot

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  Suggestions from @cl4es

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20747/files
  - new: https://git.openjdk.org/jdk/pull/20747/files/3c58fab7..a0aa9eac

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20747&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20747&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20747.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20747/head:pull/20747

PR: https://git.openjdk.org/jdk/pull/20747