Create lazy (Const)FieldElementImpl.

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

Index: pkg/analyzer/lib/src/dart/element/element.dart
diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index e0ff394da5e13346eae233032a05ee2cec5f91ed..78d0f5f496275bf18d56e98cef9fd068b33ae782 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -1534,6 +1534,13 @@ class ConstFieldElementImpl extends FieldElementImpl with ConstVariableElement {
    * Initialize a newly created field element to have the given [name].
    */
   ConstFieldElementImpl.forNode(Identifier name) : super.forNode(name);
+
+  /**
+   * Initialize using the given serialized information.
+   */
+  ConstFieldElementImpl.forSerialized(
+      UnlinkedVariable unlinkedVariable, ElementImpl enclosingElement)
+      : super.forSerialized(unlinkedVariable, enclosingElement);
 }
 
 /**
@@ -3285,6 +3292,13 @@ class FieldElementImpl extends PropertyInducingElementImpl
    */
   FieldElementImpl.forNode(Identifier name) : super.forNode(name);
 
+  /**
+   * Initialize using the given serialized information.
+   */
+  FieldElementImpl.forSerialized(
+      UnlinkedVariable unlinkedVariable, ElementImpl enclosingElement)
+      : super.forSerialized(unlinkedVariable, enclosingElement);
+
   @override
   ClassElement get enclosingElement => super.enclosingElement as ClassElement;