8012243: about 30% regression on specjvm2008.serial on 7u25 comparing 7u21

Reviewed-by: alanb, skoivu, smarks, mchung

src/share/classes/java/io/ObjectStreamClass.java

@@ -266,9 +266,11 @@ public class ObjectStreamClass implements Serializable {
         if (cl == null) {
             return null;
         }
-        Class<?> caller = Reflection.getCallerClass();
-        if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), cl.getClassLoader())) {
-            ReflectUtil.checkPackageAccess(cl);
+        if (System.getSecurityManager() != null) {
+            Class<?> caller = Reflection.getCallerClass();
+            if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), cl.getClassLoader())) {
+                ReflectUtil.checkPackageAccess(cl);
+            }
         }
         return cl;
     }

src/share/classes/java/io/ObjectStreamField.java

@@ -162,9 +162,11 @@ public class ObjectStreamField
      */
     @CallerSensitive
     public Class<?> getType() {
-        Class<?> caller = Reflection.getCallerClass();
-        if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), type.getClassLoader())) {
-            ReflectUtil.checkPackageAccess(type);
+        if (System.getSecurityManager() != null) {
+            Class<?> caller = Reflection.getCallerClass();
+            if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), type.getClassLoader())) {
+                ReflectUtil.checkPackageAccess(type);
+            }
         }
         return type;
     }