RFR: 8339934: Simplify Math.scalb(double) method [v2]

[Raffaello Giulietti]

> `Math.scalb(double)` can be simplified, removing a loop and using larger/smaller factors.

Raffaello Giulietti has updated the pull request incrementally with one additional commit since the last revision:

  Slight improvement.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20948/files
  - new: https://git.openjdk.org/jdk/pull/20948/files/dce181b4..2b7c7061

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20948&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20948&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20948.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20948/head:pull/20948

PR: https://git.openjdk.org/jdk/pull/20948