markTabActive (tab) {
    tab.style = tab.style || {}
    this.applyStyles(tab,
      {
        width: '100%',
        textAlign: 'left',
        lineHeight: '24px',
        height: '24px',
        fontSize: '14px',
        cursor: 'pointer',
        color: 'rgba(238,110,115,1)',
        transition: 'border-color .5s ease',
        borderRight: '3px solid #424242'
      }
    )
  }
Marks specified tab as active.

@returns {HTMLElement} The tab element.
@see https://github.com/Dogfalo/materialize/issues/2542#issuecomment-233458602