Reverting the BOM changes due to security concerns.

Review URL: http://codereview.chromium.org/14890

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1011 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/scanner.cc

@@ -119,18 +119,6 @@ void UTF16Buffer::PushBack(uc32 ch) {
 }
 
 
-static inline bool IsByteOrderMark(uc32 c) {
-  // The Unicode value U+FFFE is guaranteed never to be assigned as a
-  // Unicode character; this implies that in a Unicode context the
-  // 0xFF, 0xFE byte pattern can only be interpreted as the U+FEFF
-  // character expressed in little-endian byte order (since it could
-  // not be a U+FFFE character expressed in big-endian byte
-  // order). Nevertheless, we check for it to be compatible with
-  // Spidermonkey.
-  return c == 0xFEFF || c == 0xFFFE;
-}
-
-
 uc32 UTF16Buffer::Advance() {
   // NOTE: It is of importance to Persian / Farsi resources that we do
   // *not* strip format control characters in the scanner; see
@@ -138,17 +126,16 @@ uc32 UTF16Buffer::Advance() {
   //    https://bugzilla.mozilla.org/show_bug.cgi?id=274152
   //
   // So, even though ECMA-262, section 7.1, page 11, dictates that we
-  // must remove Unicode format-control characters, we only remove the BOM.
-  // This is in line with how Safari handles it.
+  // must remove Unicode format-control characters, we do not. This is
+  // in line with how IE and SpiderMonkey handles it.
   if (!pushback_buffer()->is_empty()) {
     pos_++;
     return last_ = pushback_buffer()->RemoveLast();
+  } else if (stream_->has_more()) {
+    pos_++;
+    uc32 next = stream_->GetNext();
+    return last_ = next;
   } else {
-    while (stream_->has_more()) {
-      pos_++;
-      uc32 next = stream_->GetNext();
-      if (!IsByteOrderMark(next)) return last_ = next;
-    }
     // note: currently the following increment is necessary to avoid a
     // test-parser problem!
     pos_++;
@@ -247,11 +234,25 @@ void Scanner::PushBack(uc32 ch) {
 }
 
 
+static inline bool IsByteOrderMark(uc32 c) {
+  // The Unicode value U+FFFE is guaranteed never to be assigned as a
+  // Unicode character; this implies that in a Unicode context the
+  // 0xFF, 0xFE byte pattern can only be interpreted as the U+FEFF
+  // character expressed in little-endian byte order (since it could
+  // not be a U+FFFE character expressed in big-endian byte
+  // order). Nevertheless, we check for it to be compatible with
+  // Spidermonkey.
+  return c == 0xFEFF || c == 0xFFFE;
+}
+
+
 void Scanner::SkipWhiteSpace(bool initial) {
   has_line_terminator_before_next_ = initial;
 
   while (true) {
-    while (kIsWhiteSpace.get(c0_)) {
+    // We treat byte-order marks (BOMs) as whitespace for better
+    // compatibility with Spidermonkey and other JavaScript engines.
+    while (kIsWhiteSpace.get(c0_) || IsByteOrderMark(c0_)) {
       // IsWhiteSpace() includes line terminators!
       if (kIsLineTerminator.get(c0_))
         // Ignore line terminators, but remember them. This is necessary

test/mjsunit/bom.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
-//       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.
-
-// According to section 7.1 of EcmaScript-262 format control characters
-// should be removed before parsing. We're following the discussion at
-// https://bugs.webkit.org/show_bug.cgi?id=4931 in only removing the BOM.
-// See also https://bugzilla.mozilla.org/show_bug.cgi?id=274152.
-
-// Ignores BOM (and only BOM) in string literals.
-var format_controls =
-  eval('"\uFEFF\u200F\u200E\u00AD\u2062\u200D\u200C\u200B"');
-assertEquals('\u200F\u200E\u00AD\u2062\u200D\u200C\u200B', 
-             format_controls);
-
-// Ignores BOM in identifiers.
-eval('var x\uFEFFy = 7');
-assertEquals(7, xy);
-
-// Doesn't ignore non-BOM format control characters.
-assertThrows('var y\u200Fx = 7');
-assertThrows('var y\u200Ex = 7');
-assertThrows('var y\u20ADx = 7');
-assertThrows('var y\u2062x = 7');
-assertThrows('var y\u200Dx = 7');
-assertThrows('var y\u200Cx = 7');
-assertThrows('var y\u200Bx = 7');