Check field type when evaluating initializing formals.

pkg/analyzer/lib/src/generated/element.dart

Index: pkg/analyzer/lib/src/generated/element.dart
diff --git a/pkg/analyzer/lib/src/generated/element.dart b/pkg/analyzer/lib/src/generated/element.dart
index 40da7193ffebff748145ef5890240c6dd46cf8ec..502405d0de569626dbd1abf1c49fdb3ebc585ef9 100644
--- a/pkg/analyzer/lib/src/generated/element.dart
+++ b/pkg/analyzer/lib/src/generated/element.dart
@@ -4675,7 +4675,13 @@ class FieldFormalParameterMember extends ParameterMember implements FieldFormalP
   accept(ElementVisitor visitor) => visitor.visitFieldFormalParameterElement(this);
 
   @override
-  FieldElement get field => (baseElement as FieldFormalParameterElement).field;
+  FieldElement get field {
+    FieldElement field = (baseElement as FieldFormalParameterElement).field;
+    if (field is FieldElement) {
+      return FieldMember.from(field, definingType);
+    }
+    return field;
+  }
 }
 
 /**