RFR: 8274855: vectorapi tests failing with assert(!vbox->is_Phi()) failed

[Igor Veresov]

We need to handle the case when the allocation input to `VectorBoxNode` is a phi but the vector input is not, which can definitely be the case if the vector input has been value-numbered. It seems to be safe to do by construction because `VectorBoxNode` and `VectorBoxAllocation` come in a specific order as a result of expanding an intrinsic call. After that, if any of the inputs to VectorBoxNode are value-numbered they can only move up and are guaranteed to dominate.

-------------

Commit messages:
 - Remove tests from the problem list
 - Handle the case when the allocation input to a VectorBoxNode is a phi

Changes: https://git.openjdk.java.net/jdk/pull/6162/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6162&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274855
  Stats: 11 lines in 2 files changed: 8 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6162.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6162/head:pull/6162

PR: https://git.openjdk.java.net/jdk/pull/6162