More dart2js strong mode cleanup.

pkg/compiler/lib/src/resolution/resolution.dart

Index: pkg/compiler/lib/src/resolution/resolution.dart
diff --git a/pkg/compiler/lib/src/resolution/resolution.dart b/pkg/compiler/lib/src/resolution/resolution.dart
index bcae57be407da816cacde965f61d7d52580296eb..3267764b3e1a43a9856cd89347d658f8d6a01be1 100644
--- a/pkg/compiler/lib/src/resolution/resolution.dart
+++ b/pkg/compiler/lib/src/resolution/resolution.dart
@@ -774,7 +774,8 @@ class ResolverTask extends CompilerTask {
 
     // Check that the mixed in class doesn't have any constructors and
     // make sure we aren't mixing in methods that use 'super'.
-    mixin.forEachLocalMember((AstElement member) {
+    mixin.forEachLocalMember((_member) {
+      AstElement member = _member;
       if (member.isGenerativeConstructor && !member.isSynthesized) {
         reporter.reportErrorMessage(
             member, MessageKind.ILLEGAL_MIXIN_CONSTRUCTOR);