1 files changed, 8 insertions, 1 deletions
diff --git a/js/src/jsexn.h b/js/src/jsexn.h
index a63c70909e..ae6335209b 100644
--- a/js/src/jsexn.h
+++ b/js/src/jsexn.h
@@ -85,10 +85,17 @@ ExnTypeFromProtoKey(JSProtoKey key)
 {
     JSExnType type = static_cast<JSExnType>(key - JSProto_Error);
     MOZ_ASSERT(type >= JSEXN_ERR);
-    MOZ_ASSERT(type < JSEXN_WARN);
+    MOZ_ASSERT(type < JSEXN_ERROR_LIMIT);
     return type;
 }
 
+static inline bool
+IsErrorProtoKey(JSProtoKey key)
+{
+    JSExnType type = static_cast<JSExnType>(key - JSProto_Error);
+    return type >= JSEXN_ERR && type < JSEXN_ERROR_LIMIT;
+}
+
 class AutoClearPendingException
 {
     JSContext* cx;