Revert "Create parent class loader for dex2oat"

Bug: 22858531

This reverts commit d37d364c27e74a7b49970a8c970482e273aa7b1a.

Change-Id: Id71a6f3bb9a29c04a5c13210633674e05d798114
diff --git a/runtime/class_linker.h b/runtime/class_linker.h
index 9d432c6..f1fd0c3 100644
--- a/runtime/class_linker.h
+++ b/runtime/class_linker.h
@@ -523,10 +523,7 @@
 
   // Creates a GlobalRef PathClassLoader that can be used to load classes from the given dex files.
   // Note: the objects are not completely set up. Do not use this outside of tests and the compiler.
-  // If parent_loader is null then we use the boot class loader.
-  jobject CreatePathClassLoader(Thread* self,
-                                std::vector<const DexFile*>& dex_files,
-                                jobject parent_loader)
+  jobject CreatePathClassLoader(Thread* self, std::vector<const DexFile*>& dex_files)
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!dex_lock_);