Bug 960694. Support writing out classes with JS implementations of classinfo. r=bsmedberg

--HG--
extra : rebase_source : 6eb91d99f710b366fc2ffab5defea0969834633f

xpcom/io/nsBinaryStream.cpp

@@ -261,9 +261,21 @@ nsBinaryOutputStream::WriteCompoundObject(nsISupports* aObject,
         return NS_ERROR_NOT_AVAILABLE;
 
     nsCID cid;
-    classInfo->GetClassIDNoAlloc(&cid);
+    nsresult rv = classInfo->GetClassIDNoAlloc(&cid);
+    if (NS_SUCCEEDED(rv)) {
+        rv = WriteID(cid);
+    } else {
+        nsCID *cidptr = nullptr;
+        rv = classInfo->GetClassID(&cidptr);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+            return rv;
+        }
+
+        rv = WriteID(*cidptr);
+
+        NS_Free(cidptr);
+    }
 
-    nsresult rv = WriteID(cid);
     if (NS_WARN_IF(NS_FAILED(rv)))
         return rv;