RFR(M) 8179100: [AOT] Rewrite redundant initialization elimination

[Igor Veresov]

Redundant initialization elimination can be rewritten using the dominator tree visitor pattern. This makes code much more readable. It also now handle the case of the dominating initialization of a subclass. And since now we have more time the phase requires a unit test.

Webrev: http://cr.openjdk.java.net/~iveresov/8179100/webrev.00
(It’s a complete rewrite, so don’t look at the diffs, they are messy).

I’ll be pushing this through graal-core and doing a graal update after that.

igor