Refactoring of $clinit and $init method accessors.

Change-Id: I5caab1249df99e44d0113481a596536897833a43
Review-Link: https://gwt-review.googlesource.com/#/c/1171/


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@11375 8db76d5a-ed1c-0410-87a9-c151d255dfc7