When rendering line or area charts with multiple series, we generally collect all the available X values and we automatically fill each series with missing x data points (to cover the most used case where we are rendering pre-aggregated data in Kibana).
This can cause issues when we want to keep the non-consecutive nature of the line/area. This fix removes the x filling for line and area charts in the following case: non-stacked line or area chart, with continuous scale and no fit function.
We apply this fix only to that specific case because: for stacked lines/area we need to clearly compute the stack of each data point on the x-axis, for categorical-ordinal scale (where a line/area chart doesn't always match with the best practice) the x-axis doesn't always describe a continuity within the data.

fix #825

BREAKING CHANGE: when rendering non-stacked line/area charts with a continuous x scale and no fit function,
the line/area between non-consecutive data points will be rendered as a continuous line/area without adding an uncertain dashed line/ semi-transparent area that connects the two, non-adjacent, points.

# [23.0.0](v22.0.0...v23.0.0) (2020-09-30)

### Bug Fixes

* render continuous line/area between non-adjacent points ([#833](#833)) ([9f9892b](9f9892b)), closes [#825](#825)

### Features

* debug state flag added to chart status ([#834](#834)) ([83919ff](83919ff))
* expose datum as part of GeometryValue ([#822](#822)) ([dcd7077](dcd7077))

### BREAKING CHANGES

* when rendering non-stacked line/area charts with a continuous x scale and no fit function,
the line/area between non-consecutive data points will be rendered as a continuous line/area without adding an uncertain dashed line/ semi-transparent area that connects the two, non-adjacent, points.