Fix setting array length to zero for slow elements.

test/mjsunit/regress/regress-crbug-146910.js

Index: test/mjsunit/regress/regress-crbug-146910.js
diff --git a/test/mjsunit/regress/regress-110509.js b/test/mjsunit/regress/regress-crbug-146910.js
similarity index 87%
copy from test/mjsunit/regress/regress-110509.js
copy to test/mjsunit/regress/regress-crbug-146910.js
index 132bd233bee32f6c84061049224ea43901dae06a..120f80973192fa9b5ee1db6797da6c13e4358c31 100644
--- a/test/mjsunit/regress/regress-110509.js
+++ b/test/mjsunit/regress/regress-crbug-146910.js
@@ -25,17 +25,14 @@
 // (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
+var x = [];
+assertSame(0, x.length);
+assertSame(undefined, x[0]);
 
-// Verify that LRandom preserves rsi correctly.
+Object.defineProperty(x, '0', { value: 7, configurable: false });
+assertSame(1, x.length);
+assertSame(7, x[0]);
 
-function foo() {
-  Math.random();
-  new Function("");
-}
-
-foo();
-foo();
-foo();
-%OptimizeFunctionOnNextCall(foo);
-foo();
+x.length = 0;
+assertSame(1, x.length);
+assertSame(7, x[0]);