function makeTimingFunctionEditor(cursor) {
            runs(function () {
                var promise = provider(testEditor, cursor);
                if (promise) {
                    promise.done(function (inlineResult) {
                        inlineResult.onAdded();
                        inline = inlineResult;
                    });
                    waitsForDone(promise, "open timing function editor");
                }
            });
        }
Creates an inline timing function editor connected to the given cursor position in the test editor.
Note that this does *not* actually open it as an inline editor in the test editor.
Tests that use this must wrap their contents in a runs() block.
@param {!{line:number, ch: number}} cursor Position for which to open the inline editor.
   if the provider did not create an inline editor.