To reproduce:

1. Open the project, attached by user
2. Press Play
3. Press A button, this will create new game object with Image component
4. Try to press B

Expected: creating a new game object and adding an Image component to it at runtime should not break the GraphicsRaycaster component
Actual: UI Buttons and other controls do not react to mouse click after creating a new game object and adding an Image component to it at runtime

Reproduce on 5.6.0f1, 5.6.0p1, 5.6.0p2, 2017.1.0b1
Did not reproduce on 5.5.3p1, 5.6.0b11
Regression introduced in 5.6.0f1