Mac: Fix content shell crash on startup

We don't need to register WebKitWeightWatcher fonts any more because of [1].

[1] http://src.chromium.org/viewvc/blink?view=revision&revision=164460

BUG=331629
TBR=jochen@chromium.org,eae@chromium.org

Review URL: https://codereview.chromium.org/124873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243056 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243056