ART: Speed up HGraph::PopulateIrreducibleRecursive

Populating an irreducible loop can potentially traverse all possible
paths through the HGraph, leading to an exponential algorithm.
This patch adds a bit vector of nodes whose membership in the loop
has been decided and need not be revisited again.

Bug: 27856014
Change-Id: I3696f08c846e6f40e5de44cb771811bac7e3e08a
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 0088fed..dc5a8fa 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -727,7 +727,7 @@
  private:
   // Internal recursive implementation of `Populate`.
   void PopulateRecursive(HBasicBlock* block);
-  void PopulateIrreducibleRecursive(HBasicBlock* block);
+  void PopulateIrreducibleRecursive(HBasicBlock* block, ArenaBitVector* finalized);
 
   HBasicBlock* header_;
   HSuspendCheck* suspend_check_;