Audio Clip is being played even when there is no Audio Listener component in the scene.

Steps to reproduce:
1. Create a new project.
2. Remove Audio Listener component from the Main Camera.
3. Add an Audio Source in the scene with an audio clip attached.
4. Play the scene.

Actual Result: Audio is playing in the scene.

Expected Result: Audio shouldn't be played. A warning message should be shown in the console like older Unity versions, "There are no audio listeners in the scene. Please ensure there is always one audio listener in the scene"

Reproducible On: 2018.2.0a4, 2018.3.0b5, 2019.1.0a3
Works Fine On: 2018.2.0a3, 2018.1.0

Note:
- Appears on both OSX and Windows.