[tests] Fix bogus uses of assertThrows.

test/mjsunit/regress/regress-70066.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 102 matching lines @@
 assertEquals(void 0, o.value, "test7");
 assertEquals(0, x, "test7");  // Global x is undisturbed.
 
 
 // Delete on a global property.
 function test8() {
   with ({}) { return delete x; }
 }
 
 assertEquals(true, test8(), "test8");
-assertThrows("x", "test8");  // Global x should be deleted.
+assertThrows("x");  // Global x should be deleted.
 
 
 // Delete on a property that is not found anywhere.
 function test9() {
   with ({}) { return delete x; }
 }
 
-assertThrows("x", "test9");  // Make sure it's not there.
+assertThrows("x");  // Make sure it's not there.
 assertEquals(true, test9(), "test9");
 
 
 // Delete on a DONT_DELETE property of the global object.
 var y = 10;
 function test10() {
   with ({}) { return delete y; }
 }
 
 assertEquals(false, test10(), "test10");
 assertEquals(10, y, "test10");