Fix RegExp.source for uncompiled regexp.

test/mjsunit/regress/regress-crbug-435825.js

Index: test/mjsunit/regress/regress-crbug-435825.js
diff --git a/test/mjsunit/serialize-embedded-error.js b/test/mjsunit/regress/regress-crbug-435825.js
similarity index 58%
copy from test/mjsunit/serialize-embedded-error.js
copy to test/mjsunit/regress/regress-crbug-435825.js
index 473c931b305d54dd45c01b21b8edead15a5d3b19..e10b812d4d8ea9a7cdca9687b567b3cb500c2591 100644
--- a/test/mjsunit/serialize-embedded-error.js
+++ b/test/mjsunit/regress/regress-crbug-435825.js
@@ -2,12 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// --serialize-toplevel --cache=code
+Error.prepareStackTrace = function (a,b) { return b; };
 
-var caught = false;
 try {
-  parseInt() = 0;
-} catch(e) {
-  caught = true;
+  /(invalid regexp/;
+} catch (e) {
+  e.stack[0].getThis().toString();
 }
-assertTrue(caught);