Fix re-initialization of existing double field.

test/mjsunit/regress/regress-2717.js

Index: test/mjsunit/regress/regress-2717.js
diff --git a/test/mjsunit/regress/regress-crbug-245424.js b/test/mjsunit/regress/regress-2717.js
similarity index 75%
copy from test/mjsunit/regress/regress-crbug-245424.js
copy to test/mjsunit/regress/regress-2717.js
index 005c8baba9492dd339b4fbdc3b48f7577b9c308a..4f8f7915b1c43e48235e7bd6bcb79f89957223cf 100644
--- a/test/mjsunit/regress/regress-crbug-245424.js
+++ b/test/mjsunit/regress/regress-2717.js
@@ -25,17 +25,27 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --allow-natives-syntax
+// Test re-initializing existing field which is already being tracked as
+// having double representation.
+(function() {
+  function test1(a) {
+    return { x: 1.5, x: a };
+  };
+
+  assertEquals({}, test1({}).x);
+})();
+
+// Test initializing new field which follows an existing transition to a
+// map that tracks it as having double representation.
+(function() {
+  function test1(a) {
+    return { y: a };
+  };
 
-function boom() {
-  var a = {
-    foo: "bar",
-    foo: "baz"
+  function test2(a) {
+    return { y: a };
   };
-  return a;
-}
 
-assertEquals("baz", boom().foo);
-assertEquals("baz", boom().foo);
-%OptimizeFunctionOnNextCall(boom);
-assertEquals("baz", boom().foo);
+  assertEquals(1.5, test1(1.5).y);
+  assertEquals({}, test2({}).y);
+})();