TextEncode/Decode not supported on IE11

[dhakehurst]

IE11 does not have TextEncoder/Decode built in.
thus the 'require('text-encoding')' gets executed.
But 'require' is not available on IE 11 either.

[fzhinkin]

We're rebooting the kotlinx-io development (see #131), all issues related to the previous versions will be closed. Consider reopening it if the issue remains (or the feature is still missing) in a new version.