function testOpenTimingFunction(cursor, start, end) {
                makeTimingFunctionEditor(cursor);
                runs(function () {
                    expect(inline).toBeTruthy();
                    expect(inline._startBookmark.find().ch).toBe(start);
                    expect(inline._endBookmark.find().ch).toBe(end);
                });
            }
Expects an inline editor to be opened at the given cursor position and to have the
given initial timing function (which should match the timing function at that position).
@param {!{line:number, ch:number}} cursor The cursor position to try opening the inline at.
@param {number} start The expected start of timing function.
@param {number} end The expected end of timing function.