Add an option for starting a detached process with stdio connected

sdk/lib/io/process.dart

Index: sdk/lib/io/process.dart
diff --git a/sdk/lib/io/process.dart b/sdk/lib/io/process.dart
index a977b319b6173dd8bfe70d0cf62bfb952217c7ad..ef6d8ab343d046ece7e2b8b7a406715ef89c0530 100644
--- a/sdk/lib/io/process.dart
+++ b/sdk/lib/io/process.dart
@@ -100,6 +100,18 @@ void sleep(Duration duration) {
 int get pid => _ProcessUtils._pid(null);
 
 /**
+ * Modes for running a new process.
+ */
+enum ProcessStartMode {
+  /// Normal child process.
+  NORMAL,
+  /// Detached child process.
+  DETACHED,
+  /// Detachad clild process with stdin, stdout and stderr connected.

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

clild -> child
Connected to what?

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+  DETACHED_WITH_STDIO
+}
+
+/**
  * The means to execute a program.
  *
  * Use the static [start] and [run] methods to start a new process.
@@ -258,12 +270,24 @@ abstract class Process {
    *       stderr.addStream(process.stderr);
    *     });
    *
-   * If [detach] is `true` a detached process will be created. A
-   * detached process has no connection to its parent, and can
-   * keep running on its own when the parent dies. The only
+   * If [mode] is [ProcessStartMode.NORMAL] a normal child process
+   * will be started.

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

Explain what "normal" means, or rephrase as:

If [mode] is not [ProcessStartMode.NORMAL], some features of [Process] may be
unavailable.

... then the following explains which features are missing for the other modes.

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   *
+   * If `mode` is [ProcessStartMode.DETACHED] a detached process will
+   * be created. A detached process has no connection to its parent,
+   * and can keep running on its own when the parent dies. The only
    * information available from a detached process is its `pid`. There
-   * is no connection to its `stdin`, `stdout` or `stderr` nor will its
-   * exit code become available when it terminates.
+   * is no connection to its `stdin`, `stdout` or `stderr` nor will

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

comma before "nor"?

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   * its exit code become available when it terminates.
+   *
+   * If `mode` is [ProcessStartMode.DETACHED_WITH_STDIO] a detached
+   * process will be created where the `stdin`, `stdout` and `stderr`
+   * are connected. The creator can communication with the child. When

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

can communication with the child -> 
can communicate with the child through these.

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   * these communication channels are closed the detached process will

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

Rewrite as: The detached process will keep running even if these communication
channels are closed.

Is this different from a NORMAL process? If not, no need to write it. If so, say
that a normal process will stop if the input/output is closed.

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   * keep running. Its exit code will not become available when it

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

Its -> The process'

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   * terminated.

[Lasse Reichstein Nielsen, 2015/01/30 12:11:37]

terminated -> terminates.

[Søren Gjesse, 2015/02/02 13:56:44]

Done.

+   *
+   * The default value for `mode` is `ProcessStartMode.NORMAL`.
    */
   external static Future<Process> start(
       String executable,
@@ -272,7 +296,7 @@ abstract class Process {
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
-       bool detach: false});
+       ProcessStartMode mode: ProcessStartMode.NORMAL});
 
   /**
    * Starts a process and runs it non-interactively to completion. The