We have added this for the TimeChart/FacetChart line and column series specifically (anywhere else it would have to be added separately). You can get it already from the nightly build.
http://jsfiddle.net/hxju6mgw/
var t = new TimeChart({
container: document.getElementById("demo"),
data: {
units: ["h"],
url: "https://zoomcharts.com/dvsl/data/time-chart/temperature-kuldiga-h.json"
},
series: [{
style: {
fillColor: "#09c",
fillPattern: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAQAAAC1+jfqAAAALklEQVQoz2NguMEgwQABEgxXGf5j8AlI32AgIC1BB2kGAtISDASkrzKMhgOYDwA10luBo3T8ywAAAABJRU5ErkJggg==",
lineColor: "#000"
}
}],
legend: { enabled: true }
});