Support relative paths in path dependencies.

utils/tests/pub/io_test.dart

Index: utils/tests/pub/io_test.dart
diff --git a/utils/tests/pub/io_test.dart b/utils/tests/pub/io_test.dart
index 990dd6cf774692607ebd1f79553f59fa207b9df9..912a62d1e9b43f89d4efc7b1b3723d76e52e8bfc 100644
--- a/utils/tests/pub/io_test.dart
+++ b/utils/tests/pub/io_test.dart
@@ -101,13 +101,13 @@ main() {
           createDir(path.join(temp, 'dir2'));
           writeTextFile(path.join(temp, 'dir2', 'file2.txt'), '');
           createDir(dirToList);
-          return createSymlink(path.join(temp, 'dir1'),
-                               path.join(dirToList, 'linked-dir1'));
+          return createSymlink(path.join(dirToList, 'linked-dir1'),
+                               path.join(temp, 'dir1'));
         }).then((_) {
           createDir(path.join(dirToList, 'subdir'));
           return createSymlink(
-                  path.join(temp, 'dir2'),
-                  path.join(dirToList, 'subdir', 'linked-dir2'));
+                  path.join(dirToList, 'subdir', 'linked-dir2'),
+                  path.join(temp, 'dir2'));
         }).then((_) => listDir(dirToList, recursive: true));
         expect(future, completion(unorderedEquals([
           path.join(dirToList, 'linked-dir1'),
@@ -124,7 +124,7 @@ main() {
       expect(withTempDir((temp) {
         var future = defer(() {
           writeTextFile(path.join(temp, 'file1.txt'), '');
-          return createSymlink(temp, path.join(temp, 'linkdir'));
+          return createSymlink(path.join(temp, 'linkdir'), temp);
         }).then((_) => listDir(temp, recursive: true));
         expect(future, completion(unorderedEquals([
           path.join(temp, 'file1.txt'),