ART: Convert pointer size to enum

Move away from size_t to dedicated enum (class).

Bug: 30373134
Bug: 30419309
Test: m test-art-host
Change-Id: Id453c330f1065012e7d4f9fc24ac477cc9bb9269
diff --git a/runtime/mirror/object_array.h b/runtime/mirror/object_array.h
index 4257396..a99d616 100644
--- a/runtime/mirror/object_array.h
+++ b/runtime/mirror/object_array.h
@@ -26,7 +26,7 @@
 class MANAGED ObjectArray: public Array {
  public:
   // The size of Object[].class.
-  static uint32_t ClassSize(size_t pointer_size) {
+  static uint32_t ClassSize(PointerSize pointer_size) {
     return Array::ClassSize(pointer_size);
   }