Port parser and scanner fixes from rasta branch.

pkg/front_end/lib/src/fasta/scanner/abstract_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.
 
 library fasta.scanner.abstract_scanner;
 
 import '../scanner.dart' show
-    Scanner;
+    ErrorToken,
+    Scanner,
+    buildUnexpectedCharacterToken;
+
+import 'error_token.dart' show
+    UnmatchedToken,
+    UnterminatedToken;
 
 import 'keyword.dart' show
     KeywordState,
     Keyword;
 
 import 'precedence.dart';
 
 import 'token.dart' show
-    BadInputToken,
     BeginGroupToken,
-    ErrorToken,
     KeywordToken,
     SymbolToken,
-    Token,
-    UnmatchedToken,
-    UnterminatedToken;
+    Token;
 
 import 'token_constants.dart';
 
 import 'characters.dart';
 
 abstract class AbstractScanner implements Scanner {
   final bool includeComments;
 
   /**
    * The string offset for the next token that will be created.
@@ skipping 352 matching lines @@
 
     if (identical(next, $EOF)) {
       return $EOF;
     }
     if (next < 0x1f) {
       return unexpected(next);
     }
 
     next = currentAsUnicode(next);
 
-    // The following are non-ASCII characters.
-
-    if (identical(next, $NBSP)) {
-      appendWhiteSpace(next);
-      return advance();
-    }
-
     return unexpected(next);
   }
 
   int tokenizeTag(int next) {
     // # or #!.*[\n\r]
     if (scanOffset == 0) {
       if (identical(peek(), $BANG)) {
         int start = scanOffset + 1;
         bool asciiOnly = true;
         do {
@@ skipping 652 matching lines @@
         asciiOnlyString = false;
         asciiOnlyLine = false;
       }
       next = advance();
     }
     if (!asciiOnlyLine) handleUnicode(unicodeStart);
     return unterminatedMultiLineString(quoteChar);
   }
 
   int unexpected(int character) {
-    appendErrorToken(new BadInputToken(character, tokenStart));
+    appendErrorToken(buildUnexpectedCharacterToken(character, tokenStart));
     return advanceAfterError(true);
   }
 
   int unterminated(String prefix, {bool shouldAdvance: true}) {
     appendErrorToken(new UnterminatedToken(prefix, tokenStart, stringOffset));
     return advanceAfterError(shouldAdvance);
   }
 
   int unterminatedString(int quoteChar) {
     return unterminated(new String.fromCharCodes([quoteChar]));
@@ skipping 76 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];
 }