Highstock tooltip doesn't always work when using boost

[cvasseng]

Expected behaviour

Highstock tooltips working when using boost.

Actual behaviour

Gives an exception when hovering. Problem is that it's assumed that point exists, while it doesn't when running in boost mode.

Introduced in 152e7e570.

Live demo with steps to reproduce

http://jsfiddle.net/25day6or/2/

Affected browser(s)

All.

[jon-a-nygaard]

Internal Note: In the current solbrest branch it does not error any more, but it does also not show a tooltip at all.
This is likely due to the fact that kdTree does for some reason not get built. Updated example: http://jsfiddle.net/jon_a_nygaard/25day6or/3/