The LayoutDirection class defines the constant values
for the layoutDirection style of an IStyleClient and the
layoutDirection property of an ILayoutDirectionElement.
Left-to-right layoutDirection is typically used with Latin-style
scripts. Right-to-left layoutDirection is used with scripts such as
Arabic or Hebrew.
If an IStyleClient, set the layoutDirection style to undefined to
inherit the layoutDirection from its ancestor.
If an ILayoutDirectionElement, set the layoutDirection property to null to
inherit the layoutDirection from its ancestor.