Issue #26 Part 2a: make more EME code conditional.

- Exclude missed MediaKey functions and CDMProxy code.
- Exclude EME APIs frm being built (webidl change)
- Fix tests in --disable-eme state

dom/media/MediaDecoderReader.h

@@ -24,7 +24,9 @@
 
 namespace mozilla {
 
+#ifdef MOZ_EME
 class CDMProxy;
+#endif
 class MediaDecoderReader;
 
 struct WaitForDataRejectValue
@@ -186,7 +188,9 @@ public:
   // when to call SetIdle().
   virtual void SetIdle() {}
 
+#ifdef MOZ_EME
   virtual void SetCDMProxy(CDMProxy* aProxy) {}
+#endif
 
   // Tell the reader that the data decoded are not for direct playback, so it
   // can accept more files, in particular those which have more channels than