Remove missing plugin warnings with XPCOM, fix reference to external.initModule
for OOPHM, and close memory leak in dispatch wrappers.

Patch by: sgross
Review by: jat


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@4415 8db76d5a-ed1c-0410-87a9-c151d255dfc7