Do not violate the assumption that fast-case arrays have Smi length

when transforming from slow to fast-case array elements.

This fixes issue 201:
  
   http://code.google.com/p/v8/issues/detail?id=201
   
Review URL: http://codereview.chromium.org/18711

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1135 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -5160,6 +5160,7 @@ Object* JSObject::SetElement(uint32_t index, Object* value) {
     uint32_t new_length = 0;
     if (IsJSArray()) {
       CHECK(Array::IndexFromObject(JSArray::cast(this)->length(), &new_length));
+      JSArray::cast(this)->set_length(Smi::FromInt(new_length));
     } else {
       new_length = Dictionary::cast(elements())->max_number_key() + 1;
     }

test/mjsunit/regress/regress-201.js

+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// See http://code.google.com/p/v8/issues/detail?id=201.
+
+function testsort(n) {
+  n=1*n;
+  var numbers=new Array(n);
+  for (var i=0;i<n;i++) numbers[i]=i;
+  numbers.sort();
+}
+
+testsort("5001")