Backport fix from 7.x - wrong replace transform defautExports

[diervo]

Fixes:
rollup/rollup-plugin-babel#155 which in turn fixes the ability to build babily(master)

All info is in the link above.

Until this gets merged, everyone using rollup-plugin-babel with peer dependency on 6.x will be broken.

[mention-bot]

@diervo, thanks for your PR! By analyzing the history of the files in this pull request, we identified @hzoo, @loganfsmyth and @jridgewell to be potential reviewers.

[nicolo-ribaudo]

Hi, some ours ago on slack we discussed about this bug: fixing it in babel would not fix the regression, since rollup-plugin-babel still wouldn't with Babel <= 6.25.0.
@loganfsmyth suggested to fix it in rollup-plugin-babel, checking replacing the ClassDeclaration#parentPath instead of the class itself if it is an ExportDefaultDeclaration.
https://github.com/rollup/rollup-plugin-babel/blob/3cc04d98d4045520467f3466755bc18cf213880f/src/helperPlugin.js#L5

[diervo]

Well that's why minor versions exist right? :)
Adding the workaround in rollup-plugin-babel seems much more dirty to me.

[nicolo-ribaudo]

The problem is that rollup-plugin-babel has "babel-core": "6 || 7" as a peer dependency, so it must work with every Babel 6 version. It actually did before rollup/rollup-plugin-babel#154, so it is a breaking change to drop support for Babel <= 6.25.0

[diervo]

Fair enough, but the I would argue that this PR is orthogonal and should be merged anyway as a backport from 7. Owners call, feel free to close it.

[hzoo]

Made 3.0.2 via rollup/rollup-plugin-babel#158

[hzoo]

Just going to close then

Thanks @diervo for the patch, sorry everyone for the trouble!