Ensure reducing the length of an array doesn't make it go holey.

test/mjsunit/regress/regress-delete-empty-double.js

Index: test/mjsunit/regress/regress-delete-empty-double.js
diff --git a/test/mjsunit/fast-array-length.js b/test/mjsunit/regress/regress-delete-empty-double.js
similarity index 88%
copy from test/mjsunit/fast-array-length.js
copy to test/mjsunit/regress/regress-delete-empty-double.js
index 42f2c38f49b1dd3a3c0ffa867f7db368df78e760..f7af2b1e313fb971b2bc1b500bc0da7c9e82b754 100644
--- a/test/mjsunit/fast-array-length.js
+++ b/test/mjsunit/regress/regress-delete-empty-double.js
@@ -27,11 +27,14 @@
 
 // Flags: --allow-natives-syntax
 
-// This is a regression test for overlapping key and value registers.
+a = [1.1,2.2,3.3];
+a.length = 1;
+delete a[1];
 
+assertTrue(%HasFastDoubleElements(a));
+assertFalse(%HasFastHoleyElements(a));
 
-var a = [0, 1, 2, 3, 4, 5];
-assertTrue(%HasFastSmiElements(a));
-a.length = (1 << 30);
-assertFalse(%HasFastSmiElements(a));
+delete a[0];
 
+assertTrue(%HasFastDoubleElements(a));
+assertTrue(%HasFastHoleyElements(a));