BVC's implementation of webState:didCommitNavigationWithDetails: calls [self closeFindInPage].  There are several issues with this implementation:

1) webState:didCommitNavigationWithDetails: is deprecated.

2) When fixing #1, we may decide to close the find bar when a navigation starts, rather than when it commits. This may need some experimentation in order to make a decision.

3) The current implementation closes the find bar whenever a navigation occurs in *any* WebState.  This is almost certainly a bug, and we should be looking only at navigations in the active WebState.