Remove core.art image

It is no longer used.

Test: ./art/test.py -r --optimizing
Bug: 147817558
Bug: 147819342
Change-Id: I913d7b78365d028bfcd9d876238882ebfd410682
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index 711bc59..797846e 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -206,7 +206,7 @@
   // initializers, initialize well-known classes, and creates the heap thread pool.
   virtual void FinalizeSetup();
 
-  // Returns the directory where the pre-compiled core.art can be found.
+  // Returns the directory where the pre-compiled boot.art can be found.
   static std::string GetImageDirectory();
   static std::string GetImageLocation();
   static std::string GetSystemImageFile();