Add utility methods to write the contents of a file as one operation.

Add utility methods to write the contents of a file as one operation.

We already have them for reading and it makes sense to have them for
writing as well.

We should update the positional arguments in the dart:io library to be
named optional arguments. I'd like to do that in a separate patch.

R=sgjesse@google.com
BUG=dartbug.com/4798

Committed: https://code.google.com/p/dart/source/detail?r=15149

[Søren Gjesse, 2012-11-20 13:23:34]

lgtm

https://codereview.chromium.org/11316102/diff/1/sdk/lib/io/file_impl.dart
File sdk/lib/io/file_impl.dart (right):

https://codereview.chromium.org/11316102/diff/1/sdk/lib/io/file_impl.dart#new...
sdk/lib/io/file_impl.dart:668: stream.write(bytes);
You could just do stream.close() right after stream.write and place a handler on
onClose instead of on onNoPendingWrites.

https://codereview.chromium.org/11316102/diff/1/tests/standalone/io/file_writ...
File tests/standalone/io/file_write_as_test.dart (right):

https://codereview.chromium.org/11316102/diff/1/tests/standalone/io/file_writ...
tests/standalone/io/file_write_as_test.dart:31: f.writeAsBytes(data).then((_){
Maybe expect _ is f.

https://codereview.chromium.org/11316102/diff/1/tests/standalone/io/file_writ...
tests/standalone/io/file_write_as_test.dart:34: f.writeAsBytes(data,
FileMode.APPEND).then((_) {
Ditto.

https://codereview.chromium.org/11316102/diff/1/tests/standalone/io/file_writ...
tests/standalone/io/file_write_as_test.dart:50: f.writeAsString(data).then((_){
Ditto.

https://codereview.chromium.org/11316102/diff/1/tests/standalone/io/file_writ...
tests/standalone/io/file_write_as_test.dart:53: f.writeAsString(data,
FileMode.APPEND).then((_) {
Ditto.