RFR: 8293287 add ReplayReduce flag [v2]

[Dean Long]

> Add an experimental flag to help developers "reduce" a replay file.
> 
> As a first step, I plan to simulate reduced inlining. This will output multiple "compile" lines as if the first level of inlining never happened:
> A --> B --> C
> A --> D --> E
> becomes
> B --> C
> D --> E
> Developers can repeat iteratively until the replay crash no longer reproduces.

Dean Long has updated the pull request incrementally with two additional commits since the last revision:

 - add assert
 - fix for TestVMNoCompLevel.java test failure

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10134/files
  - new: https://git.openjdk.org/jdk/pull/10134/files/b5959eb6..73d6e812

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10134&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10134&range=00-01

  Stats: 3 lines in 2 files changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10134.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10134/head:pull/10134

PR: https://git.openjdk.org/jdk/pull/10134