Revert "ART: Forbid the zygote to load code outside of system"

This reverts commit 9ef308da0ea8d1df2edf65d4957599fafcc56aeb.

Bug: 150032912
Bug: 129454856
Test: boots
Change-Id: I522b1e0e2b9116239ca206aa5c65347976eac7ab
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index b739450..3a94ef6 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1784,9 +1784,8 @@
   VLOG(startup) << "Runtime::Init exiting";
 
   // Set OnlyUseSystemOatFiles only after boot classpath has been set up.
-  if (is_zygote_ || runtime_options.Exists(Opt::OnlyUseSystemOatFiles)) {
-    oat_file_manager_->SetOnlyUseSystemOatFiles(/*enforce=*/ true,
-                                                /*assert_no_files_loaded=*/ true);
+  if (runtime_options.Exists(Opt::OnlyUseSystemOatFiles)) {
+    oat_file_manager_->SetOnlyUseSystemOatFiles(/*assert_no_files_loaded=*/ true);
   }
 
   return true;