RFR: 8274920: ProblemList 2 VectorAPI tests failing due to "assert(!vbox->is_Phi()) failed"

[Daniel D.Daugherty]

A trivial fix to ProblemList 2 VectorAPI tests failing due to "assert(!vbox->is_Phi()) failed".

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Commit messages:
 - 8274920: ProblemList 2 VectorAPI tests failing due to "assert(!vbox->is_Phi()) failed"

Changes: https://git.openjdk.java.net/jdk/pull/5853/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5853&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274920
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5853.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5853/head:pull/5853

PR: https://git.openjdk.java.net/jdk/pull/5853