If you try to search for function definitions in DownloadsPanel.jsm, you'll get a resource:///modules/DownloadsCommon.jsm threw an exception: InternalError: bad parse node in Parser.prototype.get@resource:///modules/devtools/Parser.jsm:68. This can interfere with function searching in other files (because searching isn't always constrained to the visible file only).

Oh, you'll have to disable the pretty printer first. The pretty printed file doesn't parse for a totally different reason :) (bug 964706).

Some quick investigation leads to this code not being parsed correctly by jsreflect.cpp: var foo = {}; var bar = {}; foo.prototype = { __proto__: bar }; I filed bug 965150.