Fixes following issue:

Uncaught TypeError: Cannot read property 'viewModel' of undefined
    at child.<anonymous> (http://xar15/sitecore/shell/client/Applications/Dialogs/UploadMediaDialog.js:17:42)
    at http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/sitecore-1.0.2.js:1565:40
    at Array.forEach (<anonymous>)
    at Function._.each._.forEach (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/deps/underscore/underscore.1.4.4.js:78:11)
    at child.click (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/sitecore-1.0.2.js:1563:13)
    at Object.model.viewModel.(anonymous function) [as click] (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/sitecore-1.0.2.js:646:33)
    at HTMLButtonElement.<anonymous> (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/deps/ko/knockout-2.2.1.js:2318:66)
    at HTMLButtonElement.dispatch (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/deps/jQuery/jquery-2.1.1.js:4409:9)
    at HTMLButtonElement.elemData.handle (http://xar15/sitecore/shell/client/Speak/Assets/lib/core/1.1/deps/jQuery/jquery-2.1.1.js:4095:28)