Start unraveling circularities between analyzer and front_end/kernel.

pkg/analyzer/lib/src/fasta/mock_element.dart

Index: pkg/analyzer/lib/src/fasta/mock_element.dart
diff --git a/pkg/front_end/lib/src/fasta/analyzer/mock_element.dart b/pkg/analyzer/lib/src/fasta/mock_element.dart
similarity index 98%
rename from pkg/front_end/lib/src/fasta/analyzer/mock_element.dart
rename to pkg/analyzer/lib/src/fasta/mock_element.dart
index e7bc16c9a4015fc8840a7c54f87ca09b77843e8b..137756c0894342ee81feaf0320879e62e4aa05bf 100644
--- a/pkg/front_end/lib/src/fasta/analyzer/mock_element.dart
+++ b/pkg/analyzer/lib/src/fasta/mock_element.dart
@@ -8,9 +8,9 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 
-import '../builder/builder.dart' show Builder;
+import 'package:front_end/src/fasta/builder/builder.dart' show Builder;
 
-import '../errors.dart' show internalError;
+import 'package:front_end/src/fasta/errors.dart' show internalError;
 import 'package:analyzer/src/generated/source.dart';
 
 abstract class MockElement extends Builder implements Element, LocalElement {