Suppress follow-on errors when a file is imported with either a prefix or a show clause

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

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Defines the element model. The element model describes the semantic (as
  * opposed to syntactic) structure of Dart code. The syntactic structure of the
  * code is modeled by the [AST structure](../ast/ast.dart).
  *
  * The element model consists of two closely related kinds of objects: elements
@@ skipping 1138 matching lines @@
    * Return a list containing the combinators that were specified as part of the
    * export directive in the order in which they were specified.
    */
   List<NamespaceCombinator> get combinators;
 
   /**
    * Return the library that is exported from this library by this export
    * directive.
    */
   LibraryElement get exportedLibrary;
+
+  /**
+   * Return `true` if the file referenced by the import's URI exists.
+   */
+  bool get uriExists;
 }
 
 /**
  * A field defined within a type.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class FieldElement
     implements ClassMemberElement, PropertyInducingElement {
   /**
@@ skipping 165 matching lines @@
    * `null` if there was no prefix specified.
    */
   PrefixElement get prefix;
 
   /**
    * Return the offset of the prefix of this import in the file that contains
    * this import directive, or `-1` if this import is synthetic, does not have a
    * prefix, or otherwise does not have an offset.
    */
   int get prefixOffset;
+
+  /**
+   * Return `true` if the file referenced by the import's URI exists.
+   */
+  bool get uriExists;
 }
 
 /**
  * A label associated with a statement.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class LabelElement implements Element {
   /**
    * An empty list of label elements.
@@ skipping 667 matching lines @@
   DartType get type;
 
   /**
    * Return a representation of the value of this variable, forcing the value
    * to be computed if it had not previously been computed, or `null` if either
    * this variable was not declared with the 'const' modifier or if the value of
    * this variable could not be computed because of errors.
    */
   DartObject computeConstantValue();
 }