Steps to reproduce:
1. Open original project
2. Use "Window -> UIElements -> ScrolViewTest"
3. Open Profiler, deep profiling on, Profile Editor on, start recording
4. Drag scrollbars
5. Notice spikes in profiler during mouse movement, see comments in ScrollViewTest.cs, changing the persistenceKey of root has no effect
6. Uncomment scrollView slider persistenceKey setters
7. Drag Scrollbars, observe reduced activity in profiler

Expected result: Setting the root as shown in the project should have the same effect as setting the touched elements directly.
Actual result: Setting the root as shown in the project shows more profiler activity than setting the touched elements directly.

Reproduced in: 2017.4.18f1, 2018.3.3f1, 2019.1.0a14, 2019.2.0a1