dart2js: Rename Fragment to LibrariesMap and Output to Fragment.

dart2js: Rename Fragment to LibrariesMap and Output to Fragment.

Fragment is the better name and is now used more often.

R=zarah@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42863

[floitsch, 2015-01-13 20:52:18]

floitsch@google.com changed reviewers:
+ zarah@google.com

[floitsch, 2015-01-13 20:52:19]

While trying to use the model in the old emitter I started to clash with other
things that were called "output".

With this CL we now use "Fragment" instead. I think it's a better name anyway.

Until now "Fragment" was used by the registry. That one now has the worse
"LibrariesMap" name, but it's very local and actually represents better what the
class does.

[zarah, 2015-01-14 09:46:05]

LGTM

[floitsch, 2015-01-14 12:57:15]

Committed patchset #4 (id:60001) manually as 42863 (presubmit successful).