Fix build breakages

- use platform independent path specification is test so that
  it works on windows
- skip test for precompiled and dartk builds as the test uses
  spawnUri which is not supported in these modes

Change-Id: I7b73222ae331f863a65e6f7ff30d244533f29880
Reviewed-on: https://dart-review.googlesource.com/53340
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>

runtime/tests/vm/dart/issue32950_test.dart

@@ -4,8 +4,10 @@ import 'dart:io';
 import 'package:path/path.dart' as p;
 
 main() async {
-  var path = '/tmp/other.dart';
-  new File(path).writeAsStringSync("""
+  Directory tmp = await Directory.systemTemp.createTemp("testCopy");
+  var path = "${tmp.path}/other.dart";
+  var sourceFile = new File(path);
+  sourceFile.writeAsStringSync("""
     import 'package:path/path.dart' as p;
 
     void main() => print(p.current);
@@ -16,4 +18,5 @@ main() async {
       packageConfig: p.toUri(p.absolute(".packages")),
       onExit: exitPort.sendPort);
   await exitPort.first;
+  await sourceFile.delete();
 }

runtime/tests/vm/vm.status

@@ -72,6 +72,7 @@ dart/spawn_shutdown_test: Pass, Slow # VM Shutdown test, It can take some time f
 
 [ $runtime == dart_precompiled ]
 dart/data_uri_spawn_test: SkipByDesign # Isolate.spawnUri
+dart/issue32950_test: SkipByDesign # uses spawnUri.
 
 [ $runtime != vm ]
 dart/hello_fuchsia_test: SkipByDesign # This is a test for fuchsia OS
@@ -225,6 +226,7 @@ dart/truncating_ints_test: Skip # This test cannot be run in dartkp/legacy mode
 
 [ $compiler == dartkp && ($runtime == dart_precompiled || $runtime == vm) ]
 dart/data_uri_import_test/utf16: MissingRuntimeError # UTF-16 data URIs work in dartk
+dart/issue32950_test: SkipByDesign # uses spawnUri.
 dart/redirection_type_shuffling_test: SkipByDesign # Includes dart:mirrors.
 dart/spawn_shutdown_test: SkipSlow