Camera positioning is off after changing from 2D to 3D

[nbowditch]

When switching from 2D to 3D, the camera will appear to be zoomed in close to the terrain; however, if you check viewer.scene.camera.positionCartographic.height, it will still have the same value as it did before the morph. When zooming out, the skybox is blurry and the globe loses its texture. Seems like some kind of scaling is off.

Here's a sandbox to demonstrate - notice the camera height being printed in the console at an interval of 2 seconds. Things get weird when you switch to 3D:
http://cesiumjs.org/Cesium/Apps/Sandcastle/?src=Hello%20World.html&label=Showcases&gist=ceee26395fb91033a25e79df84ddb785

Didn't look too much into it, but I'm guessing the change that introduced the bug was somewhere in this PR: #5021