ART: Disable part of reg_type_test for CMS

Disable the test for investigation. Figure out why FillHeap leaves
enough heap space available to allocate new array classes.

Test: ART_USE_READ_BARRIER=false m test-art-host-gtest-reg_type_test
Change-Id: I486651ae4bb2d96a7cc80583bc6557b88da3d9c1
diff --git a/runtime/verifier/reg_type_test.cc b/runtime/verifier/reg_type_test.cc
index fef13a2..1aa0966 100644
--- a/runtime/verifier/reg_type_test.cc
+++ b/runtime/verifier/reg_type_test.cc
@@ -689,6 +689,9 @@
 };
 
 TEST_F(RegTypeOOMTest, ClassJoinOOM) {
+  // TODO: Figure out why FillHeap isn't good enough under CMS.
+  TEST_DISABLED_WITHOUT_BAKER_READ_BARRIERS();
+
   // Tests that we don't abort with OOMs.
 
   ArenaStack stack(Runtime::Current()->GetArenaPool());