[jdk11u-dev] RFR: 8267271: Fix gc/arguments/TestNewRatioFlag.java expectedNewSize calculation

[Goetz Lindenmaier]

I backport this for parity with 11.0.17-oracle.

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Commit messages:
 - Backport 59de99d11988b7f1ab20e323f3dc4d0d49e3b7a3

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/1138/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=1138&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8267271
  Stats: 6 lines in 1 file changed: 2 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/1138.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/1138/head:pull/1138

PR: https://git.openjdk.java.net/jdk11u-dev/pull/1138