Add support for fields to the new dart backend.

pkg/analyzer2dart/lib/src/cps_generator.dart

Index: pkg/analyzer2dart/lib/src/cps_generator.dart
diff --git a/pkg/analyzer2dart/lib/src/cps_generator.dart b/pkg/analyzer2dart/lib/src/cps_generator.dart
index c9326f2458f5a6355687d38d21344b35ed5c469d..a27b429ebe750b96651950d8dbe2d8b87f8cdb56 100644
--- a/pkg/analyzer2dart/lib/src/cps_generator.dart
+++ b/pkg/analyzer2dart/lib/src/cps_generator.dart
@@ -58,7 +58,7 @@ class CpsGeneratingVisitor extends SemanticVisitor<ir.Node>
       // Visit the body directly to avoid processing the signature as
       // expressions.
       visit(node.body);
-      return irBuilder.buildFunctionDefinition(element, const []);
+      return irBuilder.buildFunctionDefinition(const []);
     });
   }