Fix double to integer conversions in runtime string indexing.

test/mjsunit/string-charat.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 30 matching lines @@
   assertEquals("t", s().charAt(void 0));
   assertEquals("t", s().charAt(false));
   assertEquals("e", s().charAt(true));
   assertEquals("", s().charAt(-1));
   assertEquals("", s().charAt(len));
   assertEquals("", s().charAt(slowIndexOutOfRange));
   assertEquals("", s().charAt(1/0));
   assertEquals("", s().charAt(-1/0));
   assertEquals("t", s().charAt(0));
   assertEquals("t", s().charAt(-0.0));
+  assertEquals("t", s().charAt(-0.1));
   assertEquals("t", s().charAt(0.4));
   assertEquals("e", s().charAt(slowIndex1));
   assertEquals("s", s().charAt(slowIndex2));
   assertEquals("t", s().charAt(3));
   assertEquals("t", s().charAt(3.4));
   assertEquals("t", s().charAt(NaN));
 
   assertEquals(116, s().charCodeAt());
   assertEquals(116, s().charCodeAt("string"));
   assertEquals(116, s().charCodeAt(null));
   assertEquals(116, s().charCodeAt(void 0));
   assertEquals(116, s().charCodeAt(false));
   assertEquals(101, s().charCodeAt(true));
   assertEquals(116, s().charCodeAt(0));
   assertEquals(116, s().charCodeAt(-0.0));
+  assertEquals(116, s().charCodeAt(-0.1));
   assertEquals(116, s().charCodeAt(0.4));
   assertEquals(101, s().charCodeAt(slowIndex1));
   assertEquals(115, s().charCodeAt(slowIndex2));
   assertEquals(116, s().charCodeAt(3));
   assertEquals(116, s().charCodeAt(3.4));
   assertEquals(116, s().charCodeAt(NaN));
   assertTrue(isNaN(s().charCodeAt(-1)));
   assertTrue(isNaN(s().charCodeAt(len)));
   assertTrue(isNaN(s().charCodeAt(slowIndexOutOfRange)));
   assertTrue(isNaN(s().charCodeAt(1/0)));
@@ skipping 168 matching lines @@
       oldResult = result;
       String.prototype.charCodeAt = function() { return 42; };
     }
     result = s.charCodeAt(1);
   }
   assertEquals(42, result);
   assertEquals(101, oldResult);
   delete String.prototype.charCodeAt;  // Restore the default.
 }
 testPrototypeChange_charCodeAt();