[es6] Correct parsing of regular expression literal flags.

src/scanner.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Features shared by parsing and pre-parsing scanners.
 
 #include "src/scanner.h"
 
 #include <stdint.h>
 
@@ skipping 1375 matching lines @@
     }
   }
   Advance();  // consume '/'
 
   literal.Complete();
 
   return true;
 }
 
 
-bool Scanner::ScanRegExpFlags() {
+Maybe<RegExp::Flags> Scanner::ScanRegExpFlags() {
   // Scan regular expression flags.
   LiteralScope literal(this);
+  int flags = 0;
   while (c0_ >= 0 && unicode_cache_->IsIdentifierPart(c0_)) {
-    if (c0_ != '\\') {
-      AddLiteralCharAdvance();
-    } else {
-      return false;
+    RegExp::Flags flag = RegExp::kNone;
+    switch (c0_) {
+      case 'g':
+        flag = RegExp::kGlobal;
+        break;
+      case 'i':
+        flag = RegExp::kIgnoreCase;
+        break;
+      case 'm':
+        flag = RegExp::kMultiline;
+        break;
+      case 'u':
+        if (!FLAG_harmony_unicode_regexps) return Nothing<RegExp::Flags>();
+        flag = RegExp::kUnicode;
+        break;
+      case 'y':
+        if (!FLAG_harmony_regexps) return Nothing<RegExp::Flags>();
+        flag = RegExp::kSticky;
+        break;
+      default:
+        return Nothing<RegExp::Flags>();
     }
+    if (flags & flag) return Nothing<RegExp::Flags>();
+    AddLiteralCharAdvance();
+    flags |= flag;
   }
   literal.Complete();
 
   next_.location.end_pos = source_pos();
-  return true;
+  return Just(RegExp::Flags(flags));
 }
 
 
 const AstRawString* Scanner::CurrentSymbol(AstValueFactory* ast_value_factory) {
   if (is_literal_one_byte()) {
     return ast_value_factory->GetOneByteString(literal_one_byte_string());
   }
   return ast_value_factory->GetTwoByteString(literal_two_byte_string());
 }
 
@@ skipping 223 matching lines @@
     backing_store_.Add(static_cast<uint8_t>((one_byte_length >> 7) | 0x80u));
   }
   backing_store_.Add(static_cast<uint8_t>(one_byte_length & 0x7f));
 
   backing_store_.AddBlock(bytes);
   return backing_store_.EndSequence().start();
 }
 
 }  // namespace internal
 }  // namespace v8