CSS rule to disable text selection highlighting?

Answer

All of the correct CSS variations are:
.noselect {
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
<p>
Selectable text.
</p>
<p class="noselect">
Unselectable text.
</p>