Optimizing: Tag arena allocations in SsaBuilder.

Replace GrowableArray with ArenaVector in SsaBuilder and
tag allocations with a new arena allocation type.

Change-Id: I27312c51d7be9d2ad02a974cce93b365c65c5fc4
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 570ce2e..54f4071 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -668,9 +668,9 @@
   }
 }
 
-void HEnvironment::CopyFrom(const GrowableArray<HInstruction*>& locals) {
-  for (size_t i = 0; i < locals.Size(); i++) {
-    HInstruction* instruction = locals.Get(i);
+void HEnvironment::CopyFrom(const ArenaVector<HInstruction*>& locals) {
+  for (size_t i = 0; i < locals.size(); i++) {
+    HInstruction* instruction = locals[i];
     SetRawEnvAt(i, instruction);
     if (instruction != nullptr) {
       instruction->AddEnvUseAt(this, i);