Fix hover icon when drag resizing a freeform window with a stylus.

getXCursorPosition() returns NaN when using a stylus. Using getX()
returns the X coordinate for pointer index 0 regardless of the pointer
identifier.

Test: manual test with a stylus and a mouse and resize a freeform window
Flag: EXEMPT minor bug fix
Fixes: 336268312
Change-Id: I3f413f7fc93876fd02340ae56a1c5c28f3d2dc4c