Non-tiled window size not always remembered correctly on wayland

Only native wayland windows (non-Xwayland) seem to be affected.

There's at least two reproducible oddities:

First:

1. Select un-maximized/-tiled window
2. Tile the window to left or right (super+left/right arrow, or dragging to the screen edge both work)
3. Untile the window with super+down arrow, or by dragging.
4. The window is now smaller than at step 1. This is easy to notice by repeating steps 2. and 3.

Second:

1. Select untiled window and resize to about 1/4 of the screen size
2. Tile the window to left edge
3. Tile the window to right edge
4. Untile the window
5. The window is now slightly smaller than half-tiled window. i.e. mutter seems to remember the half-tiled window size as unmaximized window size (+ it's slightly smaller as per the first issue).

I haven't noticed issues with maximizing/unmaximizing windows. Only half-tiling windows seems to work incorrectly.