Bug - Point chart with one date element cannot be combined with Line charts

[MendelMonteiro]

Point charts with only one element are treated differently (the date component seems to be dropped when determining the x-axis placement). This causes issues when combining the chart with other charts such as line charts.

let line = [ (DateTime.Today, 42); (DateTime.Today.AddDays(1.0), 43) ]
let onePoint = [ (DateTime.Today, 41) ]
let twoPoints = [ (DateTime.Today, 41); (DateTime.Today.AddDays(1.0), 42) ]
Chart.Combine [ Chart.Line line; Chart.Point onePoint ] // Point is not drawn in line with first line point
Chart.Combine [ Chart.Line line; Chart.Point twoPoints ] // Points are draw correctly in line with both line points