Fix bug in ByteArray.subByteArray implementation for omitted length.

Fix bug in ByteArray.subByteArray implementation for omitted length.

If length is omitted, it defaulted to the length of the byte array,
even if the start was greater than zero. It now subtracts the start
from the length to get "the length of the rest of the byte array".

Committed: https://code.google.com/p/dart/source/detail?r=13522

[karlklose, 2012-10-11 08:18:18]

LGTM with one comment.

http://codereview.chromium.org/11098065/diff/1/runtime/lib/byte_array.dart
File runtime/lib/byte_array.dart (right):

http://codereview.chromium.org/11098065/diff/1/runtime/lib/byte_array.dart#ne...
runtime/lib/byte_array.dart:1517: if (length === null) {
Use ?length here?

http://codereview.chromium.org/11098065/diff/1/tests/standalone/byte_array_te...
File tests/standalone/byte_array_test.dart (right):

http://codereview.chromium.org/11098065/diff/1/tests/standalone/byte_array_te...
tests/standalone/byte_array_test.dart:88: Expect.equals(0,
array.subByteArray(10, null).lengthInBytes());
I am not sure this is what we want and since we can detect if the argument was
given, we should probably throw.

[Lasse Reichstein Nielsen, 2012-10-11 08:25:17]

All good ideas for changing the behavior of the method, but I don't want to do
that in a bug-fix CL.
I'll add a TODO to reconsider the signature of the method (the start argument
should not be optional, and it should look more like String.substring).