RFR: 8278534: Remove some unnecessary code in MethodLiveness::init_basic_blocks

[Hamlin Li]

This is a minor patch to remove some unnecessary code in MethodLiveness::init_basic_blocks.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/6799/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6799&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278534
  Stats: 6 lines in 1 file changed: 0 ins; 6 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6799.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6799/head:pull/6799

PR: https://git.openjdk.java.net/jdk/pull/6799