Mac: Fix assertion failure on pressing the fn-key (and increase robustness).
Mac: Fix assertion failure on pressing the fn-key (and increase robustness).

Patch by viettrungluu.

BUG=http://crbug.com/18796
TEST=On a Mac with an fn key, give the web page keyboard focus and press the fn
key.


git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@23098 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser