Allow #[] and #[]= symbols.

sdk/lib/_internal/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.
 
 part of scanner;
 
 abstract class Scanner {
   Token tokenize();
 
   factory Scanner(SourceFile file, {bool includeComments: false}) {
@@ skipping 418 matching lines @@
       appendPrecedenceToken(TILDE_INFO);
       return next;
     }
   }
 
   int tokenizeOpenSquareBracket(int next) {
     // [ [] []=
     next = advance();
     if (identical(next, $CLOSE_SQUARE_BRACKET)) {
       Token token = previousToken();
-      if (token is KeywordToken &&
-          identical(token.keyword.syntax, 'operator')) {
+      if (token is KeywordToken && token.keyword.syntax == 'operator' ||
+          token is SymbolToken && token.info == HASH_INFO) {
         return select($EQ, INDEX_EQ_INFO, INDEX_INFO);
       }
     }
     appendBeginGroup(OPEN_SQUARE_BRACKET_INFO);
     return next;
   }
 
   int tokenizeCaret(int next) {
     // ^ ^=
     return select($EQ, CARET_EQ_INFO, CARET_INFO);
@@ skipping 695 matching lines @@
 
 PrecedenceInfo closeBraceInfoFor(BeginGroupToken begin) {
   return const {
     '(': CLOSE_PAREN_INFO,
     '[': CLOSE_SQUARE_BRACKET_INFO,
     '{': CLOSE_CURLY_BRACKET_INFO,
     '<': GT_INFO,
     r'${': CLOSE_CURLY_BRACKET_INFO,
   }[begin.value];
 }