Steps to reproduce:
1. Open any project
2. Click "Add Component" on any object
3. Write in something like "rig" so the filter would come up with rigidbody components
4. Create a new script and open it
5. Change something to force a compile
6. When back at Unity have the "Add component" window open before the re-compilation
7. The filter area will get flushed and even though the search bar still has "rig" written in it, the Components are not filtered.

Expected: The filter does not get reset when the "Add component" window is open during recompile.
Actual: The filter gets reset, upon next opening of the "Add component" the last searched item does not appear.

Reproduced on 2017.2.0b9, 2017.1.1p1, 2017.1.0f3, 2017.1.0b1, 2017.1.0a6
Regression introduced in: 2017.1.0a5
Does not reproduce on: 5.6.3p3, 2017.1.0a1, 2017.1.0a3, 2017.1.0a4

Notes: The older versions close the add component window before compiling and so preserve the information.