Correctly handle negative codes in String.fromCharCode()

BUG=166553

R=yangguo@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11576069

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13235 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/string.js

@@ -824,6 +824,7 @@ function StringFromCharCode(code) {
   for (i = 0; i < n; i++) {
     var code = %_Arguments(i);
     if (!%_IsSmi(code)) code = ToNumber(code) & 0xffff;
+    if (code < 0) code = code & 0xffff;
     if (code > 0x7f) break;
     %_OneByteSeqStringSetChar(one_byte, i, code);
   }

test/mjsunit/regress/regress-166553.js

+// Copyright 2012 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.
+
+// Flags: --expose_gc
+
+JSON.stringify(String.fromCharCode(1, -11).toString())
+gc();
+var s = String.fromCharCode(1, -11)
+assertEquals(65525, s.charCodeAt(1))