Shapes and annotations do not handle Date objects or strings with time zones

At the moment (version 1.25.1), data traces can handle Date objects, which will then be displayed with what seems to be the browser's timezone settings. For example, date = new Date("2017-03-30T00:00:00.000Z") used on the X-axis in a trace, with a browser in the UTC+1 timezone will be displayed as "Mar 30, 2017, 01:00", which is indeed correct.

However, that same date object cannot be used for x0/x1 in a shape on the same object.

When using date.toISOString() instead (both for data and shapes), the timezone indicator (e.g. Z) at the end of the string is ignored and the string is considered to be within the local time zone.

Here is a jsfiddle to demonstrate the problem: https://jsfiddle.net/tkhmx8Le/

Effectively, the problem is two-fold (and might lead to two separate issues):

• It would be good if shapes and annotations also supported date objects.
• ISO-8601 date parsing should take into account the Z (or generally +xxxx or +xx:xx) timezone indicator before building its internal UTC representation. This is certainly related to #1003 (and subsequent work).

Comienza reproduciendo la discrepancia de zona horaria en el JSFiddle enlazado, comparando objetos Date y cadenas ISO-8601 en data traces, shapes y annotations. Lee el trabajo relacionado en #1003 y sigue la ruta existente de análisis de fechas; se considera terminado cuando shapes y annotations acepten objetos Date y los indicadores de zona horaria se respeten de forma coherente.