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

test/mjsunit/stack-traces.js

Index: test/mjsunit/stack-traces.js
diff --git a/test/mjsunit/stack-traces.js b/test/mjsunit/stack-traces.js
index 76b73b7233f39790cd610e5abcdd9a0cea25c088..ed16100de0ae0f921e26aaa7c5c5d7bf280f6b23 100644
--- a/test/mjsunit/stack-traces.js
+++ b/test/mjsunit/stack-traces.js
@@ -213,27 +213,11 @@ function testErrorsDuringFormatting() {
   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);
 }