Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/patch_parser.dart

Index: pkg/compiler/lib/src/patch_parser.dart
diff --git a/pkg/compiler/lib/src/patch_parser.dart b/pkg/compiler/lib/src/patch_parser.dart
index 8ed2a090477a17f27feb733e7934015a4c252dfa..1f03ad4d60e443144fad3b29d1d0d14d141158a5 100644
--- a/pkg/compiler/lib/src/patch_parser.dart
+++ b/pkg/compiler/lib/src/patch_parser.dart
@@ -193,7 +193,7 @@ class PatchParserTask extends CompilerTask {
       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(
@@ -570,4 +570,4 @@ class PatchVersion {
   bool isActive(String patchTag) => tag == null || tag == patchTag;
 
   String toString() => 'PatchVersion($tag)';
-}
+}