dart2js: Added support for writing dependency information into a file.

dart2js: Added support for writing dependency information into a file.

Having a way to detect if a dart application was modified is
very useful. In particular the test infrastructure can use it
to reduce redundant dart2js compilations. In order to do that,
the dependencies of the dart application are needed.

The added code will write the dependency information to a '*.js.deps' file.

Committed: https://code.google.com/p/dart/source/detail?r=14780

[ahe, 2012-11-09 14:48:10]

Clean and simple, LGTM

Consider sorting the file names.

[ricow1, 2012-11-12 07:23:04]

LGTM, I agree with Peter, having it sorted is nicer if a human is reading this
(for debugging purposes).

[kustermann, 2012-11-12 08:06:07]

PTAL

[ahe, 2012-11-12 08:27:44]

LGTM