ve.ce.FocusableNode: Fix documentation

The constructor doesn't use any parameter named "$resizable".
And the one usage of it (ve.ce.ImageNode) doesn't pass any
arguments.

Follows-up 3fe3032.

Change-Id: I30530f4199a7c8383933be286b7b7a705c05c26c
Merge "ve.ce.FocusableNode: Fix documentation"