Re-land: Use map transitions when defining accessor properties.

test/mjsunit/regress/regress-128146.js

Index: test/mjsunit/regress/regress-128146.js
diff --git a/test/mjsunit/regress/regress-128146.js b/test/mjsunit/regress/regress-128146.js
index 5c22b4e291eb6b53e810a696ef6de42831d2c19a..730dd91065e08fcd48a0c4b5025602c3447073b0 100644
--- a/test/mjsunit/regress/regress-128146.js
+++ b/test/mjsunit/regress/regress-128146.js
@@ -25,14 +25,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Define accessor properties, resulting in an AccessorPair with 2 transitions.
 Object.defineProperty({},"foo",{set:function(){},configurable:false});
 Object.defineProperty({},"foo",{get:function(){},configurable:false});
-Object.defineProperty({},"foo",{});
-
-// From WebKit layout tests (fast/js/prototypes.html)
-var wasSet = false;
-var o = { };
-o.__defineGetter__("__proto__", function() { wasSet = true });
-o.__proto__;
-assertFalse(wasSet);
 
+// Define a data property under the same name.
+Object.defineProperty({},"foo",{});