Removed most of the RichTextAreaImplSafari implementation used only for older versions of Safari.

Patch by: jlabanca
Review by: jgw
Issue: 2813



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5639 8db76d5a-ed1c-0410-87a9-c151d255dfc7