Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/patch_parser.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.
 
 /**
  * This library contains the infrastructure to parse and integrate patch files.
  *
  * Three types of elements can be patched: [LibraryElement], [ClassElement],
  * [FunctionElement]. Patches are introduced in patch libraries which are loaded
  * together with the corresponding origin library. Which libraries that are
@@ skipping 175 matching lines @@
     // Parse [PartialClassElement] using a "patch"-aware parser instead
     // of calling its [parseNode] method.
     if (cls.cachedNode != null) return;
 
     measure(() => compiler.withCurrentElement(cls, () {
       MemberListener listener = new PatchMemberListener(compiler, cls);
       Parser parser = new PatchClassElementParser(listener);
       try {
         Token token = parser.parseTopLevelDeclaration(cls.beginToken);
         assert(identical(token, cls.endToken.next));
-      } on ParserError catch (e, s) {
+      } on ParserError catch (e) {
         // No need to recover from a parser error in platform libraries, user
         // will never see this if the libraries are tested correctly.
         compiler.internalError(
             cls, "Parser error in patch file: $e");
       }
       cls.cachedNode = listener.popNode();
       assert(listener.nodes.isEmpty);
     }));
   }
 }
@@ skipping 356 matching lines @@
 }
 
 class PatchVersion {
   final String tag;
 
   const PatchVersion(this.tag);
 
   bool isActive(String patchTag) => tag == null || tag == patchTag;
 
   String toString() => 'PatchVersion($tag)';
-}
+}