unset = function() {
          var composerIsVisible   = view.element.offsetWidth > 0 && view.element.offsetHeight > 0;
          if (view.hasPlaceholderSet()) {
            view.clear();
            view.element.focus();
            if (composerIsVisible ) {
              setTimeout(function() {
                var sel = view.selection.getSelection();
                if (!sel.focusNode || !sel.anchorNode) {
                  view.selection.selectNode(view.element.firstChild || view.element);
                }
              }, 0);
            }
          }
          view.placeholderSet = false;
          dom.removeClass(view.element, CLASS_NAME);
        }
Simulate HTML5 placeholder attribute

Needed since
   - div[contentEditable] elements don't support it
   - older browsers (such as IE8 and Firefox 3.6) don't support it at all

@param {Object} parent Instance of main wysihtml.Editor class
@param {Element} view Instance of wysihtml.views.* class
@param {String} placeholderText

@example
   wysihtml.dom.simulatePlaceholder(this, composer, "Foobar");