Add optional workingDirectory argument to Process.start.

runtime/bin/process.dart

Index: runtime/bin/process.dart
===================================================================
--- runtime/bin/process.dart	(revision 2981)
+++ runtime/bin/process.dart	(working copy)
@@ -7,12 +7,14 @@
    * Creates a new process object and starts a process running the executable
    * found at [path] with the specified [arguments]. When the process has
    * been successfully started the [startHandler] is called. If the process
-   * fails to start the [errorHandler] is called.
+   * fails to start the [errorHandler] is called. An optional 
+   * [workingDirectory] can be passed to specify where the process is run 
+   * from.

[Søren Gjesse, 2012/01/05 09:30:47]

I think there should be some additional info on the use of relative paths here.
On Linux and Mac OS the change of working directory happens before locating the
executable whereas from the Windows documentation of CreateProcess it seems that
that might not be the case. Maybe just a comment on that combining relative
paths for the executable with a working directory might work differently on
different platforms.

[Anders Johnsen, 2012/01/05 09:50:49]

Nice observation, added further comments.

    *
    * No data can be written to the process stdin and the process cannot be
    * closed nor killed before the [startHandler] has been invoked.
    */
-  Process.start(String path, List<String> arguments);
+  Process.start(String path, List<String> arguments, [String workingDirectory]);

[Søren Gjesse, 2012/01/05 09:30:47]

Maybe we should rename path to executable.

[Anders Johnsen, 2012/01/05 09:50:49]

Agreed.

 
   /**
    * Returns an input stream of the process stdout.