grid: fix issues with cycling through window sizes caused by extents

Compensation for ClientFrame extents must be applied both in computing final window dimensions for tiled windows (at is is now since the GtkFrameExtents work) and also in the if blocks for triggering window resizing with keyboard tiling. Computing ClientFrame extents either both in window rendering and in the IF blocks or in neither allows tiled windows can be cycled through 33%, 50%, and 66% width and not become unresponsive

With this applied, CSD windows (and SSD windows with compiz-core!149 (merged) applied) can once again be tiled with the keyboard to top, bottom, left, right, center, or corners and having done so be cycled between the original 50% width, 33% width, and 66% width.

Without this, on SSD windows with compiz-core!149 (merged) applied and probably with CSD windows such as gedit in master, striking the same key combination again after tiling a window instead of resizing the window will make it unresponsive, as in that case the window x,y, width, height comparisons break due to extents being added to one side of the comparison and not the other. This adds the clientFrame extents value to the comparison value so those checks and thus window size cycling work again.