Reproduction steps:
1. Open the attached project;
2. Open the main.unity scene and run it;
3. Select the Main Camera object in the Hierarchy;
4. Move the "Static Camera Quality" slider from left to right or from right to left;
5. Observe flickering Game view.

Expected results: Game view should not flicker when X-Frame assigns a different RenderTexture to the camera.
Actual results: Scene is flickering when changing quality.

Reproduced on: 5.6.0b1, 5.6.0f1, 2017.1.0a3.
Not reproduced on: 5.5.0f3, 5.5.2p2.