Fix directory test for windows

runtime/bin/directory_test.cc

Index: runtime/bin/directory_test.cc
diff --git a/runtime/bin/directory_test.cc b/runtime/bin/directory_test.cc
index 2cc4763d7b6ea5c8ea38ad23cd829361da6cd4d5..d5b81755b9f0aed2f735d7565f43dddeeda95eb7 100644
--- a/runtime/bin/directory_test.cc
+++ b/runtime/bin/directory_test.cc
@@ -18,21 +18,19 @@ UNIT_TEST_CASE(DirectoryCurrentNoScope) {
 }
 
 
-UNIT_TEST_CASE(DirectoryExists) {
-  char* current_dir = dart::bin::Directory::CurrentNoScope();
-  EXPECT_NOTNULL(current_dir);
-
-  dart::bin::Directory::ExistsResult r =
-      dart::bin::Directory::Exists(current_dir);
-  EXPECT_EQ(dart::bin::Directory::EXISTS, r);
-
-  free(current_dir);
+TEST_CASE(DirectoryCurrent) {
+  const char* current = dart::bin::Directory::Current();
+  EXPECT_NOTNULL(current);
 }
 
 
-TEST_CASE(DirectoryCurrent) {
+TEST_CASE(DirectoryExists) {
   const char* current = dart::bin::Directory::Current();
   EXPECT_NOTNULL(current);
+
+  dart::bin::Directory::ExistsResult r =
+      dart::bin::Directory::Exists(current);
+  EXPECT_EQ(dart::bin::Directory::EXISTS, r);
 }