Don't silently ignore arguments just because we don't take any.

Change-Id: Ie1d97b1b8a8a87cc8298a6de417104db324e9b47
diff --git a/libcore/tools/runner/java/dalvik/runner/TestRunner.java b/libcore/tools/runner/java/dalvik/runner/TestRunner.java
index a706d40..dce6b2d 100644
--- a/libcore/tools/runner/java/dalvik/runner/TestRunner.java
+++ b/libcore/tools/runner/java/dalvik/runner/TestRunner.java
@@ -85,6 +85,9 @@
     }
 
     public static void main(String[] args) {
+        if (args.length != 0) {
+            throw new RuntimeException("TestRunner doesn't take arguments");
+        }
         System.out.println(TestProperties.result(new TestRunner().run()));
     }
 }