Make Error.prototype.toString spec compliant; and fix various side-effect-free error printing metho…

test/mjsunit/stack-traces.js

 // Copyright 2009 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 195 matching lines @@
   assertTrue(threw, "UnintendedCallerCensorship didn't throw");
 }
 
 // If an error occurs while the stack trace is being formatted it should
 // be handled gracefully.
 function testErrorsDuringFormatting() {
   function Nasty() { }
   Nasty.prototype.foo = function () { throw new RangeError(); };
   var n = new Nasty();
   n.__defineGetter__('constructor', function () { CONS_FAIL; });
-  var threw = false;
-  try {
-    n.foo();
-  } catch (e) {
-    threw = true;
-    assertTrue(e.stack.indexOf('<error: ReferenceError') != -1,
-               "ErrorsDuringFormatting didn't contain error: ReferenceError");
-  }
-  assertTrue(threw, "ErrorsDuringFormatting didn't throw");
-  threw = false;
+  assertThrows(()=>n.foo(), RangeError);
   // Now we can't even format the message saying that we couldn't format
   // the stack frame.  Put that in your pipe and smoke it!
   ReferenceError.prototype.toString = function () { NESTED_FAIL; };
-  try {
-    n.foo();
-  } catch (e) {
-    threw = true;
-    assertTrue(e.stack.indexOf('<error>') != -1,
-               "ErrorsDuringFormatting didn't contain <error>");
-  }
-  assertTrue(threw, "ErrorsDuringFormatting didnt' throw (2)");
+  assertThrows(()=>n.foo(), RangeError);
 }
 
 
 // Poisonous object that throws a reference error if attempted converted to
 // a primitive values.
 var thrower = { valueOf: function() { FAIL; },
                 toString: function() { FAIL; } };
 
 // Tests that a native constructor function is included in the
 // stack trace.
@@ skipping 131 matching lines @@
 
 my_error = {};
 Object.preventExtensions(my_error);
 assertThrows(function() { Error.captureStackTrace(my_error); });
 
 var fake_error = {};
 my_error = new Error();
 var stolen_getter = Object.getOwnPropertyDescriptor(my_error, 'stack').get;
 Object.defineProperty(fake_error, 'stack', { get: stolen_getter });
 assertEquals(undefined, fake_error.stack);