remove node.js dependency by running the frog compiler in

tools/testing/frogpad/frogpad.dart

Index: tools/testing/frogpad/frogpad.dart
diff --git a/tools/testing/frogpad/frogpad.dart b/tools/testing/frogpad/frogpad.dart
index 1749438d62148919aa56a2da8fff09c40edf8f49..eb7850acb7ea556f1ffa7be33bccc64a5455a883 100644
--- a/tools/testing/frogpad/frogpad.dart
+++ b/tools/testing/frogpad/frogpad.dart
@@ -27,7 +27,12 @@ void main() {
   setText("input", fs.readAll(mainFile));
 
   int time1 = new Date.now().value;
-  List<String> args = ["dummy_arg1", "dummy_arg2", mainFile];
+  List<String> args = [
+      "dummy_arg1",
+      "dummy_arg2",
+      "--enable_type_checks",
+      "--enable_asserts",
+    mainFile];
   parseOptions("dummy_home_dir", args, fs);
 
   options.useColors = false;
@@ -43,10 +48,11 @@ void main() {
   };
   bool success = world.compile();
   int time2 = new Date.now().value;
-  String output = world.getGeneratedCode();
+  String output = "throw 'frogpad compilation error';\n";
   if (success) {
-    setText("output", output);
+    output = world.getGeneratedCode();
   }
+  setText("output", output);
   setText("warnings", warnings);
 
   ((time2 - time1) / 1000).toStringAsPrecision(3);