Migrated several tests from blink to V8 repository.

test/webkit/dfg-to-string-toString-becomes-bad.js

Index: test/webkit/dfg-to-string-toString-becomes-bad.js
diff --git a/test/webkit/concat-while-having-a-bad-time.js b/test/webkit/dfg-to-string-toString-becomes-bad.js
similarity index 76%
copy from test/webkit/concat-while-having-a-bad-time.js
copy to test/webkit/dfg-to-string-toString-becomes-bad.js
index dfda1e08a0b36194b787a44ee12a9693acd8aeaf..d15917a17bb7f06ad1bccf884d6402da812512de 100644
--- a/test/webkit/concat-while-having-a-bad-time.js
+++ b/test/webkit/dfg-to-string-toString-becomes-bad.js
@@ -22,10 +22,21 @@
 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 description(
-"Tests the behavior of Array.prototype.concat while the array is having a bad time due to one of the elements we are concatenating."
+"Tests that we do ToString conversions correctly when String.prototype.valueOf is initially fine but then gets clobbered."
 );
 
-Object.defineProperty(Array.prototype, 0, { writable: false });
-shouldBe("[42].concat()", "[42]");
+function foo(a) {
+    for (var i = 0; i < 100; ++i)
+        a = new String(a);
+    return a;
+}
 
+var expected = "\"hello\"";
+for (var i = 0; i < 150; ++i) {
+    if (i == 100) {
+        String.prototype.toString = function() { return 42; }
+        expected = "\"42\"";
+    }
+    shouldBe("\"\" + foo(\"hello\")", expected);
+}