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

test/mjsunit/error-tostring.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 23 matching lines @@
 
 // Test printing of cyclic errors which return the empty string for
 // compatibility with Safari and Firefox.
 
 e = new Error();
 e.name = e;
 e.message = e;
 e.stack = "Does not occur in output";
 e.arguments = "Does not occur in output";
 e.type = "Does not occur in output";
-assertEquals('', e.toString());
+assertThrows(()=>e.toString(), RangeError);
 
 e = new Error();
 e.name = [ e ];
 e.message = [ e ];
 e.stack = "Does not occur in output";
 e.arguments = "Does not occur in output";
 e.type = "Does not occur in output";
 assertEquals('', e.toString());
 
 
@@ skipping 29 matching lines @@
 assertEquals(["e2",[1,2,3,4]], testErrorToString("", "e2"));
 assertEquals(["e1: e2",[1,2,3,4]], testErrorToString("e1", "e2"));
 
 var obj = {
   get constructor () {
     assertUnreachable();
   }
 };
 
 assertThrows(function() { obj.x(); });