Fix several Windows issues.

lib/src/executable.dart

Index: lib/src/executable.dart
diff --git a/lib/src/executable.dart b/lib/src/executable.dart
index 863f306f672e01c03349298ddf37efffcd3faa6c..788a8329f4d0b4a1cfcca05b76904bb4254dc476 100644
--- a/lib/src/executable.dart
+++ b/lib/src/executable.dart
@@ -12,6 +12,7 @@ import 'package:path/path.dart' as p;
 import 'package:stack_trace/stack_trace.dart';
 
 import 'barback/asset_environment.dart';
+import 'cr_lf_remover.dart';
 import 'entrypoint.dart';
 import 'exit_codes.dart' as exit_codes;
 import 'io.dart';
@@ -127,8 +128,8 @@ Future<int> runExecutable(Entrypoint entrypoint, String package,
 
   // Note: we're not using process.std___.pipe(std___) here because
   // that prevents pub from also writing to the output streams.
-  process.stderr.listen(stderr.add);
-  process.stdout.listen(stdout.add);
+  _forwardOutput(process.stderr, stderr);
+  _forwardOutput(process.stdout, stdout);
   stdin.listen(process.stdin.add);
 
   return process.exitCode;
@@ -231,8 +232,8 @@ Future<int> runSnapshot(String path, Iterable<String> args, {recompile(),
 
     // Note: we're not using process.std___.pipe(std___) here because
     // that prevents pub from also writing to the output streams.
-    process.stderr.listen(stderr.add);
-    process.stdout.listen(stdout.add);
+    _forwardOutput(process.stderr, stderr);
+    _forwardOutput(process.stdout, stdout);
     input.listen(process.stdin.add);
 
     return process.exitCode;
@@ -261,6 +262,19 @@ void _forwardSignals(Process process) {
   }
 }
 
+/// Forwards output from a Process's output stream to the corresponding stream
+/// for pub.
+///
+/// On Windows, this replaces any CR LF sequences in the process's output with
+/// just LF to work around sdk#19334.
+void _forwardOutput(Stream<List<int>> stream, Sink<List<int>> sink) {
+  if (Platform.isWindows) {
+    log.fine("filtering out CR LF");
+    stream = const CRLFRemover().bind(stream);
+  }
+  stream.listen(sink.add);
+}
+
 /// Runs the executable snapshot at [snapshotPath].
 Future<int> _runCachedExecutable(Entrypoint entrypoint, String snapshotPath,
     List<String> args) {