Popover for analysis tasks shows up at the left edge of annotation bars in the v3 UI

Popover for analysis tasks shows up at the left edge of annotation bars in the v3 UI
https://bugs.webkit.org/show_bug.cgi?id=152389

Reviewed by Darin Adler.

Compute the x coordinate of the popover from the center of each annotation bar.

Also adjust the x coordinate to keep the popover within the charts.

* public/v3/components/interactive-time-series-chart.js:
(InteractiveTimeSeriesChart.prototype._renderChartContent):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@194234 268f45cc-cd09-0410-ab3c-d52691b4dbfc