[ALL LANG] Unlocalized error messages for the plugin name in each New xx Plugin dialog.

Description of problem:
[ALL LANG] Unlocalized error messages for the plugin name in each New xx Plugin dialog.

Version-Release number of selected component (if applicable):
6.4.0.GA ER3

How reproducible:
100%

Steps to Reproduce:
1. Click Extensions -> Plugin Management.
2. Click New from Plugins Explorer.
3. Type an exist or invalid name for the plugin, click OK.

Actual results:
Unlocalized error messages for the plugin name in each New xx Plugin dialog:
Plugin name already exists.
Invalid plugin name.

Expected results:
They should be localized.

Additional info:
Please see the attached screen-shot.