[csa] Fix CSA::ToUint32 rounding for negative HeapNumbers

test/mjsunit/string-split.js

 // Copyright 2008 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
@@ skipping 149 matching lines @@
                                        return "abc"; }};
 separator = { toString: function() { assertEquals(1, counter);
                                      counter++;
                                      return "b"; }};
 
 assertEquals(["a", "c"], String.prototype.split.call(subject, separator));
 assertEquals(2, counter);
 
 // Check ToUint32 conversion of limit.
 assertArrayEquals(["a"], "a,b,c,d,e,f".split(/,/, -4294967295));
-assertArrayEquals(["a"], "a,b,c,d,e,f".split(/,/, -4294967294.5));
+assertArrayEquals(["a", "b"], "a,b,c,d,e,f".split(/,/, -4294967294.001));
+assertArrayEquals(["a", "b"], "a,b,c,d,e,f".split(/,/, -4294967294.5));
+assertArrayEquals(["a", "b"], "a,b,c,d,e,f".split(/,/, -4294967294.999));
 assertArrayEquals(["a", "b"], "a,b,c,d,e,f".split(/,/, -4294967294));
 assertArrayEquals(["a", "b", "c"], "a,b,c,d,e,f".split(/,/, -4294967293));
 assertArrayEquals(["a", "b", "c", "d"], "a,b,c,d,e,f".split(/,/, -4294967292));
 assertArrayEquals(["a", "b", "c", "d", "e", "f"], "a,b,c,d,e,f".split(/,/, -1));