SDK summary creation generalization (pt 1).

SDK summary creation generalization (pt 1).

Steps towards generalizing summary creation bits (to allow for, among other things, flutter SDK summary creation).  API is provisional (note still in `lib/src`).

Next up:
* move result writing out of `tool/` to allow for reuse
* `SummaryBuilder.forPackageMap(..)` factory (or similar) for use in the flutter SDK case

BUG=
R=brianwilkerson@google.com, paulberry@google.com

Committed: https://github.com/dart-lang/sdk/commit/1eefb68c25d57adf77cb83dd424814df8901fd31

[pquitslund, 2016-06-08 20:45:48]

pquitslund@google.com changed reviewers:
+ brianwilkerson@google.com, paulberry@google.com

[Brian Wilkerson, 2016-06-08 21:50:05]

lgtm, but I'm not very familiar with the code, so I'm not sure that means much.

[Paul Berry, 2016-06-09 16:58:26]

lgtm

[pquitslund, 2016-06-09 19:06:40]

Description was changed from

==========
SDK summary creation generalization (pt 1).

Steps towards generalizing summary creation bits (to allow for, among other
things, flutter SDK summary creation).  API is provisional (note still in
`lib/src`).

Next up:
* move result writing out of `tool/` to allow for reuse
* `SummaryBuilder.forPackageMap(..)` factory (or similar) for use in the flutter
SDK case

BUG=
==========

to

==========
SDK summary creation generalization (pt 1).

Steps towards generalizing summary creation bits (to allow for, among other
things, flutter SDK summary creation).  API is provisional (note still in
`lib/src`).

Next up:
* move result writing out of `tool/` to allow for reuse
* `SummaryBuilder.forPackageMap(..)` factory (or similar) for use in the flutter
SDK case

BUG=
R=brianwilkerson@google.com, paulberry@google.com

Committed:
https://github.com/dart-lang/sdk/commit/1eefb68c25d57adf77cb83dd424814df8901fd31
==========

[pquitslund, 2016-06-09 19:06:42]

Committed patchset #1 (id:1) manually as
1eefb68c25d57adf77cb83dd424814df8901fd31 (presubmit successful).