accessibility module incompatible with Internet Explorer 8 and earlier

[mistergone]

Expected behaviour

Highcharts is compatible with IE6 through IE8.

Actual behaviour

Highcharts' accessibility module causes an Expected Identifier error in IE6 through IE8.

Live demo with steps to reproduce

http://jsfiddle.net/z77pa6vz/

(Note: jsfiddle has other issues when used in IE8 and earlier, but the Expected Identifier error should show up for accessibility.js)

Affected browser(s)

Internet Explorer 6, 7, and 8

Details

Internet Explorer versions 6 through 8 do not allow for the use of "reserved words" as (dot notation) object properties, though it will allow them formatted as an Array property.

In accessibility.src.js, there are two references to typeToSeriesMap.default which causes the error (default is a reserved word).

In my (somewhat limited) testing, changing the references to typeToSeriesMap['default'] bypasses the error, so that should be an easy fix. Alternatively, the property name default could be changed to any non-reserved word.

[TorsteinHonsi]

Internal note:

We should make the module fail gracefully with old IE, and make a note on the documentation page that it is not supported.

[oysteinmoseng]

Hopefully fixed now. I don't see anything in the module that suggests it should fail on old IE apart from the things fixed, so I don't think we'll need to mark it as unsupported in the docs. Will test and verify.