Updated to babel 7

[vikr01]

• Updated all babel dependencies
• context seems to no longer be part of babel functions, instead it's api and can't be null -- so I had to pass that down to @babel/preset-env Calling the function was not needed anymore.
• Now using the new development option on @babel/preset-react when envName is development
• Dropped support for node@<=4
• Updated tests-only script to run index.js

[davalapar]

Oh my fucking gawd, here it is.

Sir @ljharb would love to hear your feedback on this! ❤️ 💟 ❤️

[bjankord]

Interested to see this merged so airbnb/babel-plugin-dynamic-import-node#64 can get merged and then facebook/create-react-app#4984 can get merged. Nice work @vikr01 updating all these things!

[ajkl2533]

Would be awesome to merge this and unblock facebook/create-react-app#4984 :)

[ljharb]

Let's also remove node <= 4 from travis.yml.

[ljharb]

I've rebased the commits down a bit. Remaining issues:

[Coder-256]

Many thanks to everybody for their work here! Just wondering, is this expected to be merged soon? airbnb/babel-plugin-dynamic-import-node#64 and vuejs/vue-cli#2642 appear to be all be waiting on this, in addition to some other projects mentioned above. I understand that it is important not to rush major changes like these, but until this is merged, many projects will be unable to upgrade to Babel 7 (which has been out for a bit now). No pressure, especially not on Columbus Day weekend, just looking for an ETA 😃

[ljharb]

@Coder-256 yes, you're right that this PR is blocking those. The hope is to merge and release it soon, but it can't be hurried by asking :-)

[kibertoad]

Woohoo! Is a new version with this planned for release?

[ljharb]

@kibertoad v3 is released.