First stab at a dev server in pub using barback.

pkg/path/test/browser_test.dart

Index: pkg/path/test/browser_test.dart
diff --git a/pkg/path/test/browser_test.dart b/pkg/path/test/browser_test.dart
index 2a830c75f7e3a034209f51d3a40a100f541a5233..3e885007caca4b6fbb878e2ffa6e255580c4bbf7 100644
--- a/pkg/path/test/browser_test.dart
+++ b/pkg/path/test/browser_test.dart
@@ -12,17 +12,26 @@ main() {
   useHtmlConfiguration();
 
   group('new Builder()', () {
-    test('uses the current working directory if root is omitted', () {
+    test('uses the current directory if root and style are omitted', () {
       var builder = new path.Builder();
-      expect(builder.root, window.location.href);
+      expect(builder.root, io.Directory.current.path);
     });
 
-    test('uses URL if style is omitted', () {
+    test('uses "." if root is omitted', () {
+      var builder = new path.Builder(style: path.Style.platform);
+      expect(builder.root, ".");
+    });
+
+    test('uses the host platform if style is omitted', () {
       var builder = new path.Builder();
-      expect(builder.style, path.Style.url);
+      expect(builder.style, path.Style.platform);
     });
   });
 
+  test('Style.platform is url', () {
+    expect(path.Style.platform, path.Style.url);
+  });
+
   test('current', () {
     expect(path.current, window.location.href);
   });