Bug 1496383 - Fix state error cases of MediaRecorder to match the W3C spec r=jya

Fix a bug that the current MediaRecorder's state error cases does not match the W3C spec.
pause() and resume() should throw an INVAILD_STATE_ERR only when it is inactive state, making them
independant.
Simply changing if statements is enough because the underlying encoder object (TrackEncoder) will
ignore Suspend/Resume calls when it is already suspended/recording so there won't be side-effects by
multiple pause()/resume() calls.

Differential Revision: https://phabricator.services.mozilla.com/D7910

--HG--
extra : moz-landing-system : lando

dom/media/MediaRecorder.cpp

@@ -1385,7 +1385,7 @@ void
 MediaRecorder::Pause(ErrorResult& aResult)
 {
   LOG(LogLevel::Debug, ("MediaRecorder.Pause"));
-  if (mState != RecordingState::Recording) {
+  if (mState == RecordingState::Inactive) {
     aResult.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
@@ -1403,7 +1403,7 @@ void
 MediaRecorder::Resume(ErrorResult& aResult)
 {
   LOG(LogLevel::Debug, ("MediaRecorder.Resume"));
-  if (mState != RecordingState::Paused) {
+  if (mState == RecordingState::Inactive) {
     aResult.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }