8283784: java_lang_String::as_platform_dependent_str stores to oop in native state

Backport-of: c9a469a4591002e7f51317a8494a2df902db5bfa

Author: jyma22

src/hotspot/share/classfile/javaClasses.cpp

@@ -456,16 +456,18 @@ char* java_lang_String::as_platform_dependent_str(Handle java_string, TRAPS) {
   }
 
   char *native_platform_string;
-  { JavaThread* thread = THREAD;
-    jstring js = (jstring) JNIHandles::make_local(thread, java_string());
-    bool is_copy;
+  JavaThread* thread = THREAD;
+  jstring js = (jstring) JNIHandles::make_local(thread, java_string());
+  {
     HandleMark hm(thread);
     ThreadToNativeFromVM ttn(thread);
     JNIEnv *env = thread->jni_environment();
+    bool is_copy;
     native_platform_string = (_to_platform_string_fn)(env, js, &is_copy);
     assert(is_copy == JNI_TRUE, "is_copy value changed");
-    JNIHandles::destroy_local(js);
   }
+  JNIHandles::destroy_local(js);
+
   return native_platform_string;
 }