Improve code generation for 'bottom' and 'dynamic' arguments.

pkg/analysis_server/lib/src/services/correction/util.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.
 
 library services.src.correction.util;
 
 import 'dart:math';
 
 import 'package:analysis_server/src/protocol.dart' show SourceChange,
     SourceEdit;
@@ skipping 916 matching lines @@
 
   /**
    * Returns the text of the given range in the unit.
    */
   String getText(int offset, int length) {
     return _buffer.substring(offset, offset + length);
   }
 
   /**
    * Returns the source to reference [type] in this [CompilationUnit].
+   * May return `null` if [type] does not have a source.
    *
    * Fills [librariesToImport] with [LibraryElement]s whose elements are
    * used by the generated source, but not imported.
    */
   String getTypeSource(DartType type, Set<LibraryElement> librariesToImport) {
     StringBuffer sb = new StringBuffer();
     // just a Function, not FunctionTypeAliasElement
     if (type is FunctionType && type.element is! FunctionTypeAliasElement) {
       return "Function";
     }
+    // dynamic or BottomType
+    if (type.isDynamic || type.isBottom) {
+      return null;
+    }
     // prepare element
     Element element = type.element;
     if (element == null) {
       String source = type.toString();
       source = source.replaceAll('<dynamic>', '');
       source = source.replaceAll('<dynamic, dynamic>', '');
       return source;
     }
     // check if imported
     if (element.library != _library) {
@@ skipping 511 matching lines @@
 
   @override
   Object visitExpression(Expression node) {
     if (node is BinaryExpression && node.operator.type == groupOperatorType) {
       return super.visitNode(node);
     }
     operands.add(node);
     return null;
   }
 }