Bug 899804 - Make CPOWs handle instanceof with WebIDL interfaces (r=bz,dvander)

js/ipc/JavaScriptChild.cpp

@@ -7,6 +7,7 @@
 
 #include "JavaScriptChild.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/BindingUtils.h"
 #include "nsContentUtils.h"
 #include "xpcprivate.h"
 #include "jsfriendapi.h"
@@ -625,3 +626,27 @@ JavaScriptChild::AnswerInstanceOf(const ObjectId &objId, const JSIID &iid, Retur
 
     return ok(rs);
 }
+
+bool
+JavaScriptChild::AnswerDOMInstanceOf(const ObjectId &objId, const int &prototypeID,
+                                     const int &depth,
+                                     ReturnStatus *rs, bool *instanceof)
+{
+    AutoSafeJSContext cx;
+    JSAutoRequest request(cx);
+
+    *instanceof = false;
+
+    RootedObject obj(cx, findObject(objId));
+    if (!obj)
+        return false;
+
+    JSAutoCompartment comp(cx, obj);
+
+    JSBool tmp;
+    if (!mozilla::dom::InterfaceHasInstance(cx, prototypeID, depth, obj, &tmp))
+        return fail(cx, rs);
+    *instanceof = tmp;
+
+    return ok(rs);
+}