RFR: 8319778: Remove unreachable code in ObjectSynchronizer::exit

[David Holmes]

On Fri, 10 Nov 2023 12:04:37 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> In `ObjectSynchronizer::exit` when unlocking on an inflated monitor with `LM_LIGHTWEIGHT` there is a check if the owner is anonymous. That branch should never be take and would indicate that something is wrong with either `ObjectSynchronizer::inflate` or that `ObjectSynchronizer::exit` is trying to unlock a monitor not owned by the `current` thread.
> 
> Changes this to an assert instead. Did not condition the assert on `LM_LIGHTWEIGHT` as this property should hold regardless of locking mode.

Sorry I don't follow the rationale here. If the object is fast-locked to T1 and T2 tries to lock, it will inflate and have to install the anonymous-owner. WhenT1 exits it will see this state.

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PR Review: https://git.openjdk.org/jdk/pull/16602#pullrequestreview-1726402482