Reproduction Steps:
1. Import attached project.
2. Open "Test" scene.
3. In Hierarchy, select "Canvas" -> "RawImage".
4. In Inspector, rapidly change one of the Scale axis.

Expected result: Should give out Fatal Error message "Size overflow in allocater."
Actual result: Unity crashes. (GIF attached)

Reproducible with: 2017.1.0a6
Not reproducible with: 5.5.3f1, 5.6.0f3
Regression introduced in: 2017.1.0a3

Note: In non-reproducible versions, Unity freezes.