Fix dart2js decimal number tokenization.

tests/language/number_identifier_test.dart

 // Copyright (c) 2011, 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.
 
 import "package:expect/expect.dart";
 
 main() {
   // Integer literals.
   Expect.isTrue(2is int);
   Expect.equals(2, 2as int);
@@ skipping 13 matching lines @@
   Expect.isTrue(.2is double);
   Expect.equals(0.2, .2as double);
   Expect.isTrue(1e2is double);
   Expect.equals(1e2, 1e2as double);
   Expect.isTrue(1e-2is double);
   Expect.equals(1e-2, 1e-2as double);
   Expect.isTrue(1e+2is double);
   Expect.equals(1e+2, 1e+2as double);
   Expect.throws(() => 1.e+2,                       /// 05: ok
                 (e) => e is NoSuchMethodError);    /// 05: continued
+  1d;  /// 06: compile-time error
+  1D;  /// 07: compile-time error
+  Expect.throws(() => 1.d+2,                       /// 08: ok
+                (e) => e is NoSuchMethodError);    /// 08: continued
+  Expect.throws(() => 1.D+2,                       /// 09: ok
+                (e) => e is NoSuchMethodError);    /// 09: continued
+  1.1d;  /// 10: compile-time error
+  1.1D;  /// 11: compile-time error
   1e;  /// 02: compile-time error
   1x;  /// 03: compile-time error
 }