Add support for client/dartc compilation only tests.

runtime/bin/directory_impl.dart

Index: runtime/bin/directory_impl.dart
diff --git a/runtime/bin/directory_impl.dart b/runtime/bin/directory_impl.dart
index ee4cbaa9c04282743e4d22ff3b1f4e0803a1a256..e87cb540c64eb1911cdba87fc4bc575bf3531f5f 100644
--- a/runtime/bin/directory_impl.dart
+++ b/runtime/bin/directory_impl.dart
@@ -36,12 +36,10 @@ class _DirectoryCreateTempIsolate extends Isolate {
   void main() {
     port.receive((path, replyTo) {
       // Call function to get file name
-      replyTo.send(_createTemp(path, (Math.random() * 0x8000000).toInt()));
+      replyTo.send(_Directory._createTemp(path, (Math.random() * 0x8000000).toInt()));
       port.close();
     });
   }
-
-  String _createTemp(String template, int num) native "Directory_CreateTemp";
 }
 
 
@@ -49,6 +47,8 @@ class _Directory implements Directory {
 
   _Directory(String this._path);
 
+  static String _createTemp(String template, int num) native "Directory_CreateTemp";
+
   bool existsSync() {
     int exists = _exists(_path);
     if (exists < 0) {
@@ -80,6 +80,15 @@ class _Directory implements Directory {
     });
   }
 
+  void createTempSync() {
+    var result = _createTemp(path, (Math.random() * 0x8000000).toInt());
+    if (result != '') {
+      _path = result;
+    } else {
+      throw "createTempSync failed";
+    }
+  }
+
   void deleteSync() {
     if (!_delete(_path)) {
       throw new DirectoryException("Directory deletion failed: $_path");