Don't crash when decoding astral plane UTF-8.

Don't crash when decoding astral plane UTF-8.

Committed: https://code.google.com/p/dart/source/detail?r=14639

[Bob Nystrom, 2012-11-07 00:22:50]

I think this should address dartbug.com/6513, but please let me know if I did
something goofy here. The only effective change is to not rely on the length of
a new String.fromCharCodes() to be equivalent to the length of the list passed
to it.

Given surrogate pairs, that's no longer a reliable invariant as I understand it.

[Mads Ager (google), 2012-11-07 06:54:40]

LGTM, thanks Bob.

I'm a little worried about which other things will break in this way after the
recent String changes. But we'll just have to take them as they show up.

https://codereview.chromium.org/11364115/diff/1/sdk/lib/io/string_stream.dart
File sdk/lib/io/string_stream.dart (right):

https://codereview.chromium.org/11364115/diff/1/sdk/lib/io/string_stream.dart...
sdk/lib/io/string_stream.dart:94: } else {
Let's change this to

if (len !== null && len < available()) {
  ...
} else if (_resultOffset == 0) {
  ...
} else {
  ...
}

[Bob Nystrom, 2012-11-07 17:28:05]

https://codereview.chromium.org/11364115/diff/1/sdk/lib/io/string_stream.dart
File sdk/lib/io/string_stream.dart (right):

https://codereview.chromium.org/11364115/diff/1/sdk/lib/io/string_stream.dart...
sdk/lib/io/string_stream.dart:94: } else {
On 2012/11/07 06:54:40, Mads Ager wrote:
> Let's change this to
> 
> if (len !== null && len < available()) {
>   ...
> } else if (_resultOffset == 0) {
>   ...
> } else {
>   ...
> }
> 

Done.