dartdocs.org builds do not understand sdk_ext

[eseidel]

Presumably the SDK version being used to build it too old.

Example trying to build sky's docs and not finding dart:sky (which is defined in the sky_engine sdk_ext)
http://www.dartdocs.org/buildlogs/b-87230942e4c30b300eeac68dea654-startupscript.log

@sethladd

[sethladd]

Thanks! We'll take a look at this as soon as Dart 1.12 is out. This should work, so we'll figure it out.

[sethladd]

cc @keertip