Add 'scanGenericMethodComments' parameter to constructors and scan() functions.

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 'dart:collection' show ListMixin;
 
 import 'dart:typed_data' show Uint16List, Uint32List;
 
@@ skipping 52 matching lines @@
    */
   CommentToken comments;
 
   /**
    * A pointer to the last scanned comment token or `null` if none.
    */
   Token commentsTail;
 
   final List<int> lineStarts;
 
-  AbstractScanner(this.includeComments, {int numberOfBytesHint})
+  AbstractScanner(this.includeComments, this.scanGenericMethodComments,
+      {int numberOfBytesHint})
       : lineStarts = new LineStarts(numberOfBytesHint) {
     this.tail = this.tokens;
   }
 
   /**
    * Advances and returns the next character.
    *
    * If the next character is non-ASCII, then the returned value depends on the
    * scanner implementation. The [Utf8BytesScanner] returns a UTF-8 byte, while
    * the [StringScanner] returns a UTF-16 code unit.
@@ skipping 1204 matching lines @@
       switchToUint32(newLength);
     }
   }
 
   void switchToUint32(int newLength) {
     final newArray = new Uint32List(newLength);
     newArray.setRange(0, arrayLength, array);
     array = newArray;
   }
 }