Bug 1411685: Remove another accessibility related diagnostic crash on Nightly. r=aklotz

I missed this one in bug 1431404.
This condition is rare and does indicate a problem which breaks accessibility.
However, we aren't getting any closer to diagnosing this as a result of this crash, so it causes user pain without any gain to us.

MozReview-Commit-ID: GncQGeZckrV

--HG--
extra : rebase_source : b6670005d53bc6d0009f0b8b142c2ab837b7d2e7

ipc/mscom/ProxyStream.cpp

@@ -331,9 +331,7 @@ ProxyStream::ProxyStream(REFIID aIID, IUnknown* aObject, Environment* aEnv,
 
     marshalResult = ::CoMarshalInterface(stream, aIID, aObject, MSHCTX_LOCAL,
                                          nullptr, mshlFlags);
-#if !defined(MOZ_DEV_EDITION)
-    MOZ_DIAGNOSTIC_ASSERT(marshalResult != E_INVALIDARG);
-#endif // !defined(MOZ_DEV_EDITION)
+    MOZ_ASSERT(marshalResult != E_INVALIDARG);
     if (FAILED(marshalResult)) {
       return;
     }