RFR: 8320128: Clean up Parse constructor for OSR

[Xin Liu]

There's a special case for the constructor of Parse. If current compilation is OSR and it is handling the top-level method(depth() == 1), then

1. _tf = C->tf();
2. _entry_bci = C->entry_bci();
3. _flow = method()->get_osr_flow_analysis(_entry_bci);

We don't need to assign those member data twice. We can also factor out _flow->failing() for the special case and normal cases. 

It's worth mentioning that we can't save ciTypeFlow computation because
get_osr_flow_analysis(_entry_bci) actually needs get_flow_analysis(method()).

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Commit messages:
 - 8320128: Clean up Parse constructor for OSR

Changes: https://git.openjdk.org/jdk/pull/16669/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16669&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320128
  Stats: 35 lines in 1 file changed: 14 ins; 17 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/16669.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16669/head:pull/16669

PR: https://git.openjdk.org/jdk/pull/16669