Issue 24459. Fix for 'Create Method' QF in different unit.

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 125 matching lines @@
     Token commentToken = token.precedingComments;
     while (commentToken != null) {
       ranges.add(rangeToken(commentToken));
       commentToken = commentToken.next;
     }
     token = token.next;
   }
   return ranges;
 }
 
+/**
+ * Return the given [element] if it is a [CompilationUnitElement].
+ * Return the enclosing [CompilationUnitElement] of the given [element],
+ * maybe `null`.
+ */
+CompilationUnitElement getCompilationUnitElement(Element element) {
+  if (element is CompilationUnitElement) {
+    return element;
+  }
+  return element.getAncestor((e) => e is CompilationUnitElement);
+}
+
 String getDefaultValueCode(DartType type) {
   if (type != null) {
     String typeName = type.displayName;
     if (typeName == "bool") {
       return "false";
     }
     if (typeName == "int") {
       return "0";
     }
     if (typeName == "double") {
@@ skipping 278 matching lines @@
   }
   return parents;
 }
 
 /**
  * Returns a parsed [AstNode] for the given [classElement].
  *
  * The resulting AST structure may or may not be resolved.
  */
 AstNode getParsedClassElementNode(ClassElement classElement) {
-  CompilationUnitElement unitElement =
-      classElement.getAncestor((e) => e is CompilationUnitElement);
+  CompilationUnitElement unitElement = getCompilationUnitElement(classElement);

[Brian Wilkerson, 2015/09/30 00:48:31]

Not sure what value this refactoring has. The method is only being used in one
place and involves an unnecessary type check (which is expensive).

   CompilationUnit unit = getParsedUnit(unitElement);
   int offset = classElement.nameOffset;
   AstNode classNameNode = new NodeLocator(offset).searchWithin(unit);
   if (classElement.isEnum) {
     return classNameNode.getAncestor((node) => node is EnumDeclaration);
   } else {
     return classNameNode.getAncestor(
         (node) => node is ClassDeclaration || node is ClassTypeAlias);
   }
 }
@@ skipping 1109 matching lines @@
 
   @override
   Object visitExpression(Expression node) {
     if (node is BinaryExpression && node.operator.type == groupOperatorType) {
       return super.visitNode(node);
     }
     operands.add(node);
     return null;
   }
 }