Create synthetic FieldElement(s) (don't use non-synthetic ones) for non-synthetic class getters/set…

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

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index b111583ccf056103a2041e3db0f5681a5abeb9df..9b3b7fbb74a296f054288149846758798b35d9f6 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -3143,14 +3143,14 @@ class ElementHolder {
     _typeParameters.add(element);
   }
 
-  FieldElement getField(String fieldName) {
+  FieldElement getField(String fieldName, {bool synthetic: false}) {
     if (_fields == null) {
       return null;
     }
     int length = _fields.length;
     for (int i = 0; i < length; i++) {
       FieldElement field = _fields[i];
-      if (field.name == fieldName) {
+      if (field.name == fieldName && field.isSynthetic == synthetic) {
         return field;
       }
     }