Parse metadata, but ignore it.

dart/lib/compiler/implementation/scanner/scanner.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface Scanner {
   Token tokenize();
 }
 
 /**
  * Common base class for a Dart scanner.
@@ skipping 213 matching lines @@
     if (next === $CLOSE_CURLY_BRACKET) {
       return appendEndGroup(CLOSE_CURLY_BRACKET_INFO, "}",
                             OPEN_CURLY_BRACKET_TOKEN);
     }
 
     if (next === $SLASH) {
       return tokenizeSlashOrComment(next);
     }
 
     if (next === $AT) {
-      return tokenizeRawString(next);
+      return tokenizeAtOrRawString(next);
     }
 
     if (next === $DQ || next === $SQ) {
       return tokenizeString(next, byteOffset, false);
     }
 
     if (next === $PERIOD) {
       return tokenizeDotsOrNumber(next);
     }
 
@@ skipping 420 matching lines @@
           next = nextByte();
         } while (next > 127);
         String string = utf8String(nonAsciiStart, -1).slowToString();
         isAscii = false;
         int byteLength = nonAsciiStart - byteOffset;
         addToCharOffset(string.length - byteLength);
       }
     }
   }
 
-  int tokenizeRawString(int next) {
+  int tokenizeAtOrRawString(int next) {
     int start = byteOffset;
     next = advance();
     if (next === $DQ || next === $SQ) {
       return tokenizeString(next, start, true);
     } else {
-      throw new MalformedInputException("expected ' or \"", charOffset);
+      appendPrecedenceToken(AT_INFO);
+      return next;
     }
   }
 
   int tokenizeString(int next, int start, bool raw) {
     int quoteChar = next;
     next = advance();
     if (quoteChar === next) {
       next = advance();
       if (quoteChar === next) {
         // Multiline string.
@@ skipping 134 matching lines @@
                                       charOffset);
   }
 }
 
 class MalformedInputException {
   final String message;
   final position;
   MalformedInputException(this.message, this.position);
   toString() => message;
 }