New syntax of inline mixin reference

[vbradnitski]

@alansemenov commented on Mon Jul 30 2018

Inline mixins are now referenced via this syntax:

<inline mixin=“my-inline-mixin” />

Since we now support only one type of mixins (inline) and for consistency with syntax of x-data reference, change supported syntax to:

<mixin name=“my-inline-mixin” />