[openjfx11] Review request for 8206899: DRT crashes randomly when running 'dom/html/level2/html/AppletsCollection.html'

[Arunprasad Rajkumar]

Hi,

Please review the following fix,

https://bugs.openjdk.java.net/browse/JDK-8206899 <https://bugs.openjdk.java.net/browse/JDK-8206899>

http://cr.openjdk.java.net/~arajkumar/8206899/webrev <http://cr.openjdk.java.net/~arajkumar/8206899/webrev>

Root-cause: 
Problem is due to the following statement in `void PluginWidgetJava::updatePluginWidget()` 

jobject obj = platformWidget(); 

platformWidget method returns temporary JGObject as a value and it’s life time is restricted with in the same line. 

Proposed solution: 
Change the `obj` type to JLObject, so that it will hold the ref object as local variable in the function scope. 

JLObject obj = platformWidget(); 

Thanks,
Arun