RFR: 8258059: Clean up MethodData::profile_unsafe

[Claes Redestad]

Following up on comments to #1733 

- Simplify by using Symbol::starts_with
- Bytecode_invoke methods are not inlineable, so locals avoid redundant calls

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Commit messages:
 - 8258059: Clean up MethodData::profile_unsafe

Changes: https://git.openjdk.java.net/jdk/pull/1740/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1740&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258059
  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1740.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1740/head:pull/1740

PR: https://git.openjdk.java.net/jdk/pull/1740