Reproduction Steps:
1. Import attached project.
2. Open "test" scene.
3. Enter Play mode.
4. In Hierarchy, drag "Filled Simple 1" from Assets folder into Canvas.
5. In Profiler, observe GC Allocated in Memory.
6. Activate Image objects in Canvas.
7. Drag "Filled Simple 1" into Canvas again.
8. Observe GC Allocated.

Expected result: GC Allocated spikes should not become larger.
Actual result: GC Allocated spikes become 10 times larger.

Reproducible with: 5.6.0f3, 2017.1.0b1
Not reproducible with: 5.5.3p1
Regression introduced in: 5.6.0b8