ObjPtr<>-ify mirror::CallSite.

And remove unused function CallSite::Create().

Test: m test-art-host-gtest
Test: testrunner.py --host --interpreter
Bug: 31113334
Change-Id: I936cda76543fb79edda1c2cc8671b0684fb9f08a
diff --git a/runtime/mirror/call_site.h b/runtime/mirror/call_site.h
index be5bdc9..ca9a9ee 100644
--- a/runtime/mirror/call_site.h
+++ b/runtime/mirror/call_site.h
@@ -18,6 +18,7 @@
 #define ART_RUNTIME_MIRROR_CALL_SITE_H_
 
 #include "mirror/method_handle_impl.h"
+#include "obj_ptr.h"
 
 namespace art {
 
@@ -28,13 +29,7 @@
 // C++ mirror of java.lang.invoke.CallSite
 class MANAGED CallSite : public Object {
  public:
-  static mirror::CallSite* Create(Thread* const self,
-                                  Handle<MethodHandle> method_handle)
-      REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Roles::uninterruptible_);
-
-  MethodHandle* GetTarget() REQUIRES_SHARED(Locks::mutator_lock_) {
-    return GetFieldObject<MethodHandle>(TargetOffset());
-  }
+  ObjPtr<MethodHandle> GetTarget() REQUIRES_SHARED(Locks::mutator_lock_);
 
  private:
   static inline MemberOffset TargetOffset() {