Integration test for record recoverability from buffering

[clabe45]

When an input layer's source points to a WebRTC video or audio stream and when recording the movie the stream starts, then buffers due to network connectivity issues and then resumes, the recording shouldn't include the buffering time. If the test fails, no need to fix the code unless you want to.

See also:

• Pause media recorder when waiting to load during playback #192