Adjustments to accommodate changes in Find dialog.

Remove mFindHeight, and the associated adjustements. It
is no longer needed because the FindDialog is no longer
on top of the WebView; instead, the WebView is resized to
accommodate it.
Do not take focus if the user touches the WebView while
Find is up.
Add a (hidden) getter to check to see if Find is showing.

Requires a change to packages/apps/Browser

Change-Id: I08cedb02d29eeeaac6860aa0933ccab43ed5c39f