This bug is to follow up on fix failure of JDK-8039315

The fix does not work on Linux platform ( it is OK on Windows and Mac platforms)

*** Tested Environment:
- x86 Ubuntu 12.04/ 32-bit FF 30.x
- x64 Ubuntu 12.04/ 64-bit FF 30.x
- jre 8u20-b23 promotion (32-bit and 64-bit)

*** Steps to reproduce:
0) On Linux, install jre 8u20-b23
1) Invoke Java Control Panel---< Advanced and make sure 'Enable' is selected for Mixed code verification
2) Add http://rehte.cn.oracle.com:8080 to the Exception Site Listin Java Control Panel
3) Use Firefox to load the mixed-code test applet:
 http://rehte.cn.oracle.com:8080/wshost/new_framework_exe/new_framework/tests/plugin/mixedcode/html/testMixedCodeDialogBehavior.html
4) Accept to warning dialogs

Expected: Mixed-code dialogs prompted
Actual: No mixed-code dialog displayed

Completed detail can be found in the original bug: JDK-8039315

The issue does not happen on Windows or Mac platforms