Move json to lib/json/{json.dart, json_frog.dart}

Move json to lib/json/{json.dart, json_frog.dart}
Committed: https://code.google.com/p/dart/source/detail?r=4101

[dgrove, 2012-02-09 22:50:43]

codereview.chromium.org is not showing completely accurate status. Here's the
actual gcl status for this change:

M      frog/tests/frog/src/FrogServerTest.dart
M      frog/server/frog_server.dart
D      frog/server/dart_json.dart
D      frog/lib/json_frog.dart
D      frog/lib/frog_json_sources.gypi
M      frog/reader.dart
M      tools/create_sdk.py
M      samples/chat/chat_server_lib.dart
M      samples/chat/chat_stress_client.dart
M      samples/belay/tests/bcap_tests.dart
M      samples/belay/bcap/src/impl_bcap.dart
M      samples/belay/bcap/bcap_client.dart
M      samples/belay/bcap/bcap_fling.dart
M      samples/tests/samples/src/chat/ChatServerTest.dart
M      samples/tests/samples/src/chat/HttpTest.dart
A      lib/json
A  +   lib/json/json_frog.dart
A  +   lib/json/json.dart
D      client/json/dart_json.dart

[Siggi Cherem (dart-lang), 2012-02-09 22:50:51]

lgtm

[dgrove, 2012-02-09 23:09:40]

(adding Mark for changes in editor)

[jwren, 2012-02-09 23:37:31]

On 2012/02/09 23:09:40, dgrove wrote:
> (adding Mark for changes in editor)

Devon (devoncarew) and myself just looked at the change, it doesn't look like it
will break the editor.  If it does, just ping Devon or Mark to fix it.