Make "rect" basic type left, right, top, bottom writable

QML basic type rect has properties for left, right, top, bottom corresponding to the respective QRect or QRectF properties.

While the properties are documented as "read-only", writing to them produces no runtime error whatsoever leaving you wonder why it's not working.

I think those values should be writable from QML, so you can save yourself some client-side logic when you just want to move one of the edges of a rectangle without having to manually alter its size afterwards.

However, this could lead to people doing stupid things like

Foo {
    size.x: 100
    size.left: 150
} 

If adding this isn't desirable, then at least it should throw a TypeError like it normally does when trying to assign to a read-only property