Bugzilla

### Beta/Release Uplift Approval Request
* **User impact if declined**: Fewer users will get Software WebRender in 89 late beta and release than desired.
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: A common reason many users get Basic compositing in release is because we tried D3D11 compositing and failed. This patch allows users to fallback from D3D11 to Software WebRender instead. We are already shipping Software WebRender to users in release, and would like to expand our population to include more users.
* **String changes made/needed**:

### Beta/Release Uplift Approval Request
* **User impact if declined**: Fewer users will get Software WebRender in 89 late beta and release than desired.
* **Is this code covered by automated tests?**: Yes
* **Has the fix been verified in Nightly?**: No; I manually verified via a try build with a release configuration. It can only be verified in late beta and release configurations.
* **Needs manual test from QE?**: No
* **If yes, steps to reproduce**: 
* **List of other uplifts needed**: None
* **Risk to taking this patch**: Low
* **Why is the change risky/not risky? (and alternatives if risky)**: A common reason many users get Basic compositing in release is because we tried D3D11 compositing and failed. This patch allows users to fallback from D3D11 to Software WebRender instead. We are already shipping Software WebRender to users in release, and would like to expand our population to include more users.
* **String changes made/needed**: