dist/amd.riotx+riot.js
function createIfDirective(dom, tag, attr) {
      return create(IfExpr).init(dom, tag, attr)
    }
function createIfDirective(dom, tag, attr) {
      return create(IfExpr).init(dom, tag, attr)
    }
function createIfDirective ( dom , tag , attr ) { return create ( IfExpr ) . init ( dom , tag , attr ) }
Create a new if directive
@param   { HTMLElement } dom - if root dom node
@param   { Tag } context - tag instance where the DOM node is located
@param   { String } attr - if expression
@returns { IFExpr } a new IfExpr object
Create a new if directive