code: function MaterialTab(tab, ctx) {
      if (tab) {
          if (ctx.element_.classList.contains(ctx.CssClasses_.MDL_JS_RIPPLE_EFFECT)) {
              var rippleContainer = document.createElement('span');
              rippleContainer.classList.add(ctx.CssClasses_.MDL_RIPPLE_CONTAINER);
              rippleContainer.classList.add(ctx.CssClasses_.MDL_JS_RIPPLE_EFFECT);
              var ripple = document.createElement('span');
              ripple.classList.add(ctx.CssClasses_.MDL_RIPPLE);
              rippleContainer.appendChild(ripple);
              tab.appendChild(rippleContainer);
          }
          tab.addEventListener('click', function (e) {
              e.preventDefault();
              ctx.resetTabState_();
              tab.classList.add(ctx.CssClasses_.ACTIVE_CLASS);
          });
      }
  }
docs: Constructor for an individual tab.
  
  @constructor
  @param {Element} tab The HTML element for the tab.
  @param {MaterialTabs} ctx The MaterialTabs object that owns the tab.