Change default format to produce output that can be passed between isolates

Change default format to produce output that can be passed between isolates

R=jmesserly@google.com

Committed: https://code.google.com/p/dart/source/detail?r=22686

[Alan Knight, 2013-05-13 23:27:03]

Change the default serialization format (SimpleMapFormat) to not include
Reference objects, but to convert them into Maps so it can be passed between
isolates easily. Create an InternalMapFormat that returns the version that has
References, mostly useful for testing or if you want a format that does minimal
formatting work on top of the basic serializing. Adds a test that sends to an
isolate.

[Jennifer Messerly, 2013-05-14 00:21:38]

lgtm

https://codereview.chromium.org/14566015/diff/1/pkg/serialization/lib/src/for...
File pkg/serialization/lib/src/format.dart (right):

https://codereview.chromium.org/14566015/diff/1/pkg/serialization/lib/src/for...
pkg/serialization/lib/src/format.dart:119: forAllStates(ReaderOrWriter w,
Function predicate, Function transform) {
more precise types for the function args?

e.g. 

  "bool predicate(item), transform(item)"

another idea, could declare these via typedefs

https://codereview.chromium.org/14566015/diff/1/pkg/serialization/lib/src/for...
pkg/serialization/lib/src/format.dart:124: if (predicate(value)) {
-2 indent here. Since it's a function, usually is nice to pretend it's a block,
that way "for (x in items) { ... }" and "items.forEach((x) { ... });" have same
level of indent for their bodies.

[Alan Knight, 2013-05-14 16:34:27]

Committed patchset #2 manually as r22686 (presubmit successful).