Add Ctrl + Shift + S to Predicates

[Brent Long]

Need Ctrl-Shift-S in predicates.

Something like this:

CTRL_SHIFT_S: function({ ctrlKey, metaKey, keyCode, shiftKey }){
        return ((ctrlKey === true || metaKey === true) && shiftKey === true && keyCode === 83);
}

[Blaine Bublitz]

Assigning to @urbantumbleweed