RFR JDK-8245785: javax.swing.JTabbedPane cannot be deserialized

[Prasanta Sadhukhan]

Hi All,

Please review a fix for an issue where deserializing a serialized 
JTabbedPane-object results in NullPointerException.

The NPE is result of tabbed "pages" object not being instantiated when 
deserialized.

Proposed fix is to add a null check for "pages" object.

Bug: https://bugs.openjdk.java.net/browse/JDK-8245785

webrev: http://cr.openjdk.java.net/~psadhukhan/8245785/webrev.0/

Regards
Prasanta