Running from Mac MiniBrowser's inspector console:

InspectorFrontendHost.save("file:///~/Desktop/foo.txt", "test", true)

will cause the following error:

TypeError: 'undefined' is not a function (evaluating 'InspectorFrontendAPI.savedURL("file://localhost/Users/burg/Desktop/foo.txt ")')

This is called from WebInspectorFrontendClient::save (in WebCoreSupport/WebInspectorClient.mm). It was introduced in https://bugs.webkit.org/show_bug.cgi?id=105547.

It seems like the InspectorFrontendAPI.savedURL function is not being exposed to script, or the savedURL callback is being executed in the wrong script context.