Optimizing: Tag arena allocations in HGraph.

Replace GrowableArray with ArenaVector in HGraph and related
classes HEnvironment, HLoopInformation, HInvoke and HPhi,
and tag allocations with new arena allocation types.

Change-Id: I3d79897af405b9a1a5b98bfc372e70fe0b3bc40d
diff --git a/compiler/optimizing/codegen_test.cc b/compiler/optimizing/codegen_test.cc
index 72c67f5..5fc305c 100644
--- a/compiler/optimizing/codegen_test.cc
+++ b/compiler/optimizing/codegen_test.cc
@@ -193,7 +193,7 @@
                              bool has_result,
                              Expected expected) {
   // Tests may have already computed it.
-  if (graph->GetReversePostOrder().IsEmpty()) {
+  if (graph->GetReversePostOrder().empty()) {
     graph->BuildDominatorTree();
   }
   SsaLivenessAnalysis liveness(graph, codegen);