dart2js: Fix hints in code base.

pkg/compiler/lib/src/dart_types.dart

Index: pkg/compiler/lib/src/dart_types.dart
diff --git a/pkg/compiler/lib/src/dart_types.dart b/pkg/compiler/lib/src/dart_types.dart
index 47138acc990af0f9a59aabdd561ec0664b0e3974..21fbc7826d300b75a83cd2c0161b35462095471b 100644
--- a/pkg/compiler/lib/src/dart_types.dart
+++ b/pkg/compiler/lib/src/dart_types.dart
@@ -15,7 +15,6 @@ import 'elements/modelx.dart'
          TypeDeclarationElementX,
          TypedefElementX;
 import 'elements/elements.dart';
-import 'helpers/helpers.dart';  // Included for debug helpers.
 import 'ordered_typeset.dart' show OrderedTypeSet;
 import 'util/util.dart' show CURRENT_ELEMENT_SPANNABLE, equalElements;
 
@@ -1594,8 +1593,6 @@ class Types implements DartTypes {
     List<DartType> bNamedParameterTypes = b.namedParameterTypes;
     int aIndex = 0;
     int bIndex = 0;
-    int prefixLength =
-        min(aNamedParameterTypes.length, bNamedParameterTypes.length);
     while (aIndex < aNamedParameters.length &&
            bIndex < bNamedParameters.length) {
       String aNamedParameter = aNamedParameters[aIndex];