Uglifyjs configuration for elm 0.19

[andys8]

Description

This PR addressed the changed discussed in #314. There might be still room in terms of shaving some bytes off, but this looks fine so far. I basically did comparisons to make sure we're not moving in the wrong direction.

# UglifyJsPlugin with settings of this PR
17.280 as  1 Nov 21:50 main.516c338b.chunk.js

# Unminified results (by disabling UglifyJsPlugin)
110.583 as  1 Nov 21:54 main.516c338b.chunk.js 

# elm-minify executed on unminified results
17.289 as  1 Nov 21:55 main.516c338b.chunk.min.js

# master without DEAD_CODE_ELIMINATION
29.660 as  1 Nov 22:20 main.9e0ba63c.chunk.js

# master with DEAD_CODE_ELIMINATION
17.876 as  1 Nov 22:21 main.9e0ba63c.chunk.js

Changes

• Removes DEAD_CODE_ELIMINATION env
• Changed chapter in docs
• Sourcemaps disabled by default in prod build
• Uglify settings
  • Based on elm docs
  • 2 Passes

Testing

• Build application and executed it
• Ran npm run test

Solves #314

[andys8]

Appveyor build looks flakey. Ignoring it for now, because it looks unrelated.

[halfzebra]

Good stuff! 👍

Just one little thing, I think the source-map setup should be kept in its original state. It would be better to make it configurable from the config file, but it's a task for a different PR.

[andys8]

Okay, no prob. I'll change it back.

[halfzebra]

Looks good, thanks for working on this! 👍