Inline sources contents in source map files

[alexkirsz]

Changes proposed in this pull request:

• Inline sources contents in source map files.

The current behavior is for .map files to refer to the source file. The issue is that the src directory is not part of the NPM package, which makes this package's source maps useless as they point to non-existent files. This causes a lot of warnings with source-map-loader.

This proposed change makes it so the content of source files gets inlined in the .map files, so there is no actual need to read the source files.

Another way to do this would be to bundle the src directory within the NPM package.

[apollo-cla]

@alexkirsz: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[MrTibbles]

+1 to this getting merged.

[MrTibbles]

This is a better solution than #560 IMO

[hwillson]

Thanks @alexkirsz!