Chrome specific issue that happens when destroying a chart and re-creating it immediately (same animation frame?). The CSS animation used to detect when the canvas become visible is not re-evaluated, breaking responsiveness. Accessing the `offsetParent` property will force a reflow and re-evaluate the CSS animation.
New `options.resolve` helper that determines the final value to use from an array of input values (fallback) and a given context and/or index. For now, only the bubble chart support scriptable options, see documentation for details.
Add scriptable options documentation and update the bubble chart dataset properties table with their scriptable and indexable capabilities and default values. Also move point style description under the element configuration section.
The original implementation tries to intercept events from the chart internal iframe, which ones failing on Chrome 60. Checking internals doesn't seem the best approach, instead we could consider that a chart has been resized after the resize method has been called and processed. So let's hook `Chart.resize` and callback once it's done.
Attempt to make easier the creation of unit tests that check the drawing output. Until now, this was done by checking calls on a 'fake' context, which is hard to maintain (need to update pixel values by hands) and also not reliable when optimizing code (i.e. different calls sequence but same result).
As of now, it's possible to define 'auto' tests based on JSON/PNG fixtures: chart is generated from the JSON file and compared to the associated PNG image. The image diff is done using `pixelmatch`. As an example (and in preparation of the `filler` plugin), add auto tests for the line element `fill` options.
`karma.conf.ci.js` has been merged into `karma.conf.js` for local testing consistency: `gulp unittestWatch` has been replaced by `gulp unittest --watch` and thus use exactly the same config file. Upgrade to latest jasmine and karma packages and remove deprecated `gulp-karma` dependency (directly use `karma.Server` in gulp).
Split `test/mockContext.js` into smaller `test/jasmine.*` modules to make easier unit tests maintenance and finally, move all `*.test.js` files under the `test/specs` folder.
