mozilla/rhino — pull request #79 by anba (2012-08-12 12:00:19+00:00)
Title: Patch for Bug 608235 ("Incorrect error message for undefined[undefined]")

To ensure a user-friendly representation is being used, ScriptRuntime.toString() is now called for each argument. Also added undefDeleteError() to get all undefXError() code at a single location in the ScriptRuntime class.