Rollback uglify3 -> uglify2

[marvinhagemeister]

Seems like uglify3's behaviour has changed with regards to mangling properties. This reverts uglify back to v2.

Fixes #1075

[coveralls]

Coverage remained the same at 100.0% when pulling a0bfaf3 on marvinhagemeister:rollback_uglify into f9eb4ce on developit:master.

[marvinhagemeister]

Here is a comparison between 8.2.7 and 8.2.8. Only difference in the build artefact is an unnecessary regex escape that has been removed. Apart from that everything is identical:

[ForsakenHarmony]

hmm interesting

[developit]

+1 for the test. I had thought for some reason we already had this test!

[marvinhagemeister]

@developit We have one that checks if the non-transpiled files have the correct exports, but not one that checks the transpiled output

[marvinhagemeister]

I've played around with uglifyjs@3 a bit more, but still haven't had any success. There is a flag to list properties that should not be mangled (--mangle-props reserved=['foo','bar']) but I have trouble getting the options object and checks to reliably work.

I'll merge this, so that we can make a 8.2.9 hotfix release. After that we can look how to upgrade to uglifyjs@3 or if we should switch to GCC.