Fair enough - I've put together a test.
Here's the code: http://codepen.io/momothemonster/pen/ukLeb
Unfortunately, Cocoon doesn't seem to work with codepen.io at all, so I've uploaded the tests to a server of mine.
Working: http://mmmlabs.com/serve/gstest/index.html
Non-Working: http://mmmlabs.com/serve/gstest/gsap.html
The scene should display an image and tween it to the upper-left corner of the stage. If you load these two urls in the browser, index.html will display a non-moving image, and gsap.html will display the image and then move it. If you load them into Cocoon using Webview/Canvas2D, index.html will display a non-moving image, and gsap.html will display nothing at all.
The only difference is the call to TweenLite in gsap.html.