Increase coverage testing of sparse arrays. Add a set...

test/mjsunit/array-splice-webkit.js

Index: test/mjsunit/array-splice-webkit.js
===================================================================
--- test/mjsunit/array-splice-webkit.js	(revision 1704)
+++ test/mjsunit/array-splice-webkit.js	(working copy)
@@ -57,4 +57,13 @@
 assertArrayEquals(['c'], arr.splice(2, 100))
 assertArrayEquals(['a','b'], arr);
 
+// Verify preservation of the hole while shifting
+arr = ['a','b','c','d','e'];
+assertTrue(3 in arr);
+assertTrue(delete arr[3]);
+assertFalse(3 in arr);
+res = arr.splice(2,2);
+assertArrayEquals(['a','b','e'], arr);
+assertArrayEquals(['c',,], res);
+assertFalse(1 in res);