Nikolai Mavrenkov already created a good description of the problem on Stack Overflow: http://stackoverflow.com/questions/36893449/textarea-placeholder-isnt-shown-in-ie-11-being-rendered-using-react

I just can confirm it breaks in IE11, but works in IE10 (and other browsers) with React v15.0.2.

if (!RESERVED_PROPS.hasOwnProperty(propKey)) {
            markup = DOMPropertyOperations.createMarkupForCustomAttribute(propKey, propValue);
          }
        } else {
          markup = DOMPropertyOperations.createMarkupForProperty(propKey, propValue);
        }
        if (markup) {
          ret += ' ' + markup;
        }
      }
    }
    
    
    if (transaction.renderToStaticMarkup) {
      return ret;
    }
    if (!this._hostParent) {
      ret += ' ' + DOMPropertyOperations.createMarkupForRoot();
    }
    ret += ' ' + DOMPropertyOperations.createMarkupForID(this._domID);
    return ret;
  },
  /**
   * Creates markup for the content between the tags.
   *
   * @private
   * @param {ReactReconcileTransaction|ReactServerRenderingTransaction} transaction
   * @param {object} props
   * @param {object} context
   * @return {string} Content markup.