Clean up imports in analysis_server and analyzer_cli (and one missed in analyzer)

pkg/analysis_server/lib/src/services/correction/source_range.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.source_range_factory;
 
+import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/ast.dart';
-import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 SourceRange rangeElementName(Element element) {
   return new SourceRange(element.nameOffset, element.nameLength);
 }
 
 SourceRange rangeEndEnd(a, b) {
   int offset = a.end;
@@ skipping 58 matching lines @@
 
 SourceRange rangeStartStart(a, b) {
   int offset = a is int ? a : a.offset;
   var length = (b is int ? b : b.offset) - offset;
   return new SourceRange(offset, length);
 }
 
 SourceRange rangeToken(Token token) {
   return new SourceRange(token.offset, token.length);
 }