Revert following changes for fixing Primetime issue:

- Issue #26 Part 2a: make more EME code conditional. (99118e38e)
- Issue #26 - Part 2b: Stub out GMPDecryptorProxy functions. (d44c61bf6)
- Issue #26 - Part 2c: Remove dependence on gmp/widevine-adapter/* (4c9689f68)
- Issue #1392 - Change --enable-eme to MOZ_ARG_ENABLE_BOOL and remove MOZ_EME_MODULES (832d84d2c)
- [Basilisk] Issue MoonchildProductions/UXP#1392 - Remove usage of MOZ_EME_MODULES (3a165cd)
- Issue #65 - Remove AppConstants from toolkit/mozapps/extensions (758618b60)

dom/webidl/moz.build

@@ -282,7 +282,15 @@ WEBIDL_FILES = [
     'MediaDeviceInfo.webidl',
     'MediaDevices.webidl',
     'MediaElementAudioSourceNode.webidl',
+    'MediaEncryptedEvent.webidl',
     'MediaError.webidl',
+    'MediaKeyError.webidl',
+    'MediaKeyMessageEvent.webidl',
+    'MediaKeys.webidl',
+    'MediaKeySession.webidl',
+    'MediaKeysRequestStatus.webidl',
+    'MediaKeyStatusMap.webidl',
+    'MediaKeySystemAccess.webidl',
     'MediaList.webidl',
     'MediaQueryList.webidl',
     'MediaRecorder.webidl',
@@ -546,6 +554,7 @@ WEBIDL_FILES = [
     'WebKitCSSMatrix.webidl',
     'WebSocket.webidl',
     'WheelEvent.webidl',
+    'WidevineCDMManifest.webidl',
     'WifiOptions.webidl',
     'WindowOrWorkerGlobalScope.webidl',
     'WindowRoot.webidl',
@@ -572,19 +581,6 @@ WEBIDL_FILES = [
     'XULElement.webidl',
 ]
 
-if CONFIG['MOZ_EME']:
-    WEBIDL_FILES += [
-        'MediaEncryptedEvent.webidl',
-        'MediaKeyError.webidl',
-        'MediaKeyMessageEvent.webidl',
-        'MediaKeys.webidl',
-        'MediaKeySession.webidl',
-        'MediaKeysRequestStatus.webidl',
-        'MediaKeyStatusMap.webidl',
-        'MediaKeySystemAccess.webidl',
-        'WidevineCDMManifest.webidl',
-    ]
-
 if CONFIG['MOZ_WEBEXTENSIONS']:
   WEBIDL_FILES += ['AddonManager.webidl']