Clean up ScopedArenaAllocatorAdapter.

Make the adapter equality-comparable, define aliases for
containers using the adapter and use those aliases.
Fix DebugStackIndirectTopRefImpl assignment.

Change-Id: I689aa8a93d169f63a659dec5040567d7b1343277
diff --git a/compiler/utils/debug_stack.h b/compiler/utils/debug_stack.h
index 2e02b43..1bb0624 100644
--- a/compiler/utils/debug_stack.h
+++ b/compiler/utils/debug_stack.h
@@ -118,7 +118,7 @@
     CheckTop();
   }
   DebugStackIndirectTopRefImpl& operator=(const DebugStackIndirectTopRefImpl& other) {
-    CHECK(ref_ == other->ref_);
+    CHECK(ref_ == other.ref_);
     CheckTop();
     return *this;
   }