In JsonEncoder, test if map has only string keys, and use toEncodable if not.

In JsonEncoder, test if map has only string keys, and use toEncodable if not.

Currently the encoder assumes that a map will have string keys, and will fail
in ugly ways if it doesn't. With this change, the toEncodable function used on
other un-encodable values is also used on non-String-keyed maps.

BUG= http://dartbug.com/23469
R=sgjesse@google.com

Committed: https://github.com/dart-lang/sdk/commit/25a16a39b351f6716d4197ae92f86396b6fa97d1

[Lasse Reichstein Nielsen, 2015-05-26 11:40:08]

lrn@google.com changed reviewers:
+ sgjesse@google.com

[Søren Gjesse, 2015-05-26 14:54:01]

lgtm

https://codereview.chromium.org/1153893004/diff/1/sdk/lib/convert/json.dart
File sdk/lib/convert/json.dart (right):

https://codereview.chromium.org/1153893004/diff/1/sdk/lib/convert/json.dart#n...
sdk/lib/convert/json.dart:697: var result = writeMap(object);
result -> success

[Lasse Reichstein Nielsen, 2015-05-27 08:42:18]

PTAL

[Søren Gjesse, 2015-05-27 08:45:04]

lgtm

https://codereview.chromium.org/1153893004/diff/40001/tests/lib/convert/json_...
File tests/lib/convert/json_toEncodable_reviver_test.dart (right):

https://codereview.chromium.org/1153893004/diff/40001/tests/lib/convert/json_...
tests/lib/convert/json_toEncodable_reviver_test.dart:48: var enc = new
JsonEncoder((x) => "fixed");
x -> _

[Lasse Reichstein Nielsen, 2015-05-27 08:49:25]

Committed patchset #4 (id:60001) manually as
25a16a39b351f6716d4197ae92f86396b6fa97d1 (presubmit successful).