Material properties sometimes do not update when editor window looses focus during playmode

To reproduce:
1. Open the attached project "850927repro"
3. Enter playmode and notice the material animating
4. Minimize the editor and open some other window
5. Return to the editor

Result: Material properties do not update

Note: another way to reproduce this is to open "test" script add a whitespace and save the changes then return to the editor to let the script recompile

Reproduced on: 2017.1.0a6, 5.6.0f3, 5.5.3f1, 5.4.4p4