sourceMap.content "auto" option

[connorjclark]

overview

Implements #3219

--source-map "content=auto"

Allows for easier composition of source maps.

If an input file specifies a sourceMappingURL comment, the source map will be fetched.
If there is no comment, given an input file of src/file.js, the map will be looked for
at src/file.js.map and src/file.map. Maps can fetched via HTTP too.

--source-map "content=auto,contents=file1.js*file1.js.map|file2.js*path/to/map.js.map|..."

Allows for overriding the auto resolution strategy.

other stuff

Open to a different format for sourceMap.contents.

This is a super set of the other source map content options. I suggest removing those in a new major version, and making this "auto" behavior the default.

MOCHA_GREP='locations over auto' SKIP_COMPRESS_TESTS=1 npm test

I needed a way to quickly run the new tests I added. Should be self explanatory.

[connorjclark]

Can't get it passing on node v0.10. child_process.execSync does not exist in that version. Suggestions?

[connorjclark]

Been using this in production for awhile. Any feedback from project maintainers?