Create a new AstFactory class to be used by analyzer and its clients.

pkg/analyzer/lib/src/dart/ast/ast.dart

Index: pkg/analyzer/lib/src/dart/ast/ast.dart
diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
index 4d388d218c492ab67c070c3d67224a5976100891..5904292ad1c0c38f19feb909c93a81a7254b0bf4 100644
--- a/pkg/analyzer/lib/src/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -10668,7 +10668,6 @@ abstract class UriBasedDirectiveImpl extends DirectiveImpl
     _uri = _becomeParentOf(uri as AstNodeImpl);
   }
 
-  @override
   UriValidationCode validate() {
     return validateUri(this is ImportDirective, uri, uriContent);
   }
@@ -10710,15 +10709,15 @@ abstract class UriBasedDirectiveImpl extends DirectiveImpl
 /**
  * Validation codes returned by [UriBasedDirective.validate].
  */
-class UriValidationCodeImpl implements UriValidationCode {
+class UriValidationCode {
   static const UriValidationCode INVALID_URI =
-      const UriValidationCodeImpl('INVALID_URI');
+      const UriValidationCode('INVALID_URI');
 
   static const UriValidationCode URI_WITH_INTERPOLATION =
-      const UriValidationCodeImpl('URI_WITH_INTERPOLATION');
+      const UriValidationCode('URI_WITH_INTERPOLATION');
 
   static const UriValidationCode URI_WITH_DART_EXT_SCHEME =
-      const UriValidationCodeImpl('URI_WITH_DART_EXT_SCHEME');
+      const UriValidationCode('URI_WITH_DART_EXT_SCHEME');
 
   /**
    * The name of the validation code.
@@ -10728,7 +10727,7 @@ class UriValidationCodeImpl implements UriValidationCode {
   /**
    * Initialize a newly created validation code to have the given [name].
    */
-  const UriValidationCodeImpl(this.name);
+  const UriValidationCode(this.name);
 
   @override
   String toString() => name;