Clean-up: Removed an unused forward declaration in text_elider.h.

Let me TBR because this change is so trivial.

TBR=asvitkine@chromium.org
TEST=none

Review URL: https://codereview.chromium.org/121153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242516 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242516