Fix native extensions located in packages on Windows.

Fix native extensions located in packages on Windows.

BUG=dartbug.com/16205
R=sgjesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32102

[Bill Hesse, 2014-01-28 20:31:31]

The reported bug was in extensions with a package: url for the Dart part of the
extension.  Fixed by making the package resolution for the dll return a URL with
a url-type path, not a windows path, as the path part.

Now tested with relative, absolute, and package urls for the extension.

[kustermann, 2014-01-28 21:58:38]

https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart
File runtime/bin/builtin.dart (right):

https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart#new...
runtime/bin/builtin.dart:223: resolved = new
Uri.file(_filePathFromPackageUri(resolved));
I thought you can have package roots which are HTTP urls. Which means, that you
would need to fetch the .so/.dll file and store it in a temporary place and load
it then.

If you can have HTTP urls as package-roots then this is broken!

[Bill Hesse, 2014-01-28 22:06:35]

On 2014/01/28 21:58:38, kustermann wrote:
> https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart
> File runtime/bin/builtin.dart (right):
> 
>
https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart#new...
> runtime/bin/builtin.dart:223: resolved = new
> Uri.file(_filePathFromPackageUri(resolved));
> I thought you can have package roots which are HTTP urls. Which means, that
you
> would need to fetch the .so/.dll file and store it in a temporary place and
load
> it then.
> 
> If you can have HTTP urls as package-roots then this is broken!

I don't think we can have HTTP urls as package-roots, because the normal
resolution case, to get a script for a package URI, also goes through
this function, and can only get a file path, not an http path.

[Bill Hesse, 2014-01-28 22:55:40]

Addressed Martin's comment.

https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart
File runtime/bin/builtin.dart (right):

https://codereview.chromium.org/135403007/diff/1/runtime/bin/builtin.dart#new...
runtime/bin/builtin.dart:223: resolved = new
Uri.file(_filePathFromPackageUri(resolved));
On 2014/01/28 21:58:38, kustermann wrote:
> I thought you can have package roots which are HTTP urls. Which means, that
you
> would need to fetch the .so/.dll file and store it in a temporary place and
load
> it then.
> 
> If you can have HTTP urls as package-roots then this is broken!

Yes.  It was also broken earlier, but I have changed the CL to include a check.

[Søren Gjesse, 2014-01-29 00:16:16]

lgtm

[Bill Hesse, 2014-01-29 05:07:35]

Committed patchset #2 manually as r32102 (presubmit successful).