RFR: 8257509: Strengthen requirements to call G1HeapVerifier::verify(VerifyOption) [v2]

[Thomas Schatzl]

> Hi all,
> 
>   can I have reviews for this little change to strengthen the requirements for calling G1HeapVerifier::verify(VerifyOption)?
> 
> In particular, instead of the failed attempt to abort verification if we are not at a safepoint, assert that we are at a safepoint.
> 
> Testing: tier1-5 with no failures
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  sjohanss review, remove newline

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1590/files
  - new: https://git.openjdk.java.net/jdk/pull/1590/files/2fba7cc3..93da0d17

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1590&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1590&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1590.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1590/head:pull/1590

PR: https://git.openjdk.java.net/jdk/pull/1590