RFR: 8278261: runtime/SelectionResolution/* tests failing in loom repo

[Coleen Phillimore]

Simple bug after all.  When doing default method processing, the cpCache pointer in the constant pool is null so the on_stack query returned false.  Tested with tier1 with the wrapper and loom-tier1,loom-tier2

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Commit messages:
 - 8278261: runtime/SelectionResolution/* tests failing in loom repo

Changes: https://git.openjdk.java.net/loom/pull/88/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=88&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278261
  Stats: 5 lines in 1 file changed: 1 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/loom/pull/88.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/88/head:pull/88

PR: https://git.openjdk.java.net/loom/pull/88