When building standalone Dart executable, put implementation of dart:io natives in a separate libra…

When building standalone Dart executable, put implementation of dart:io natives in a separate library.

BUG=

Committed: https://code.google.com/p/dart/source/detail?r=14679

[Bill Hesse, 2012-11-07 15:25:03]

This refactoring of the build makes it possible to add libraries to the
implementation of dart:io without making the snapshot generator dependent on
them.

The snapshot generator uses a few C++ implementations of File and Directory
operations when building snapshots, even when building snapshots that don't
include builtins.  So these remain in the builtins library.

[Mads Ager (google), 2012-11-08 09:32:26]

LGTM with comments.

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/bin.gypi
File runtime/bin/bin.gypi (right):

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/bin.gypi#newcod...
runtime/bin/bin.gypi:309: 'dependencies': [
Can you leave this out since it is empty?

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/bin.gypi#newcod...
runtime/bin/bin.gypi:459: 'libdart_io',
Move this up to after libdart_builtin and leave generate_snapshot_file as the
last one?

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/bin.gypi#newcod...
runtime/bin/bin.gypi:545: 'builtin_fulllib.cc',
Would it be better to do the naming the other way around.

builtin.cc remains the one that has everything.
builtin_nolib.cc remains the one that has everything but no source code.
builtin_gen_snapshot.cc is the new one which has only the stuff needed for
snapshot generation.

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/builtin.cc
File runtime/bin/builtin.cc (right):

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/builtin.cc#newc...
runtime/bin/builtin.cc:56: // This is for use in the snapshot generator, which
must not link with
Instead of focusing this comment on the problem caused by the dependency, maybe
write that the snapshot generator does not need most of the dart:io C++ code and
should be indenpendent of it.

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/builtin_natives.cc
File runtime/bin/builtin_natives.cc (right):

http://codereview.chromium.org/11360121/diff/4001/runtime/bin/builtin_natives...
runtime/bin/builtin_natives.cc:21: V(Crypto_GetRandomBytes, 1)                  
                               \
I think these first two can be moved too?