fix completion replacement offset/length for invalid token in switch statement

pkg/analysis_server/test/services/completion/completion_target_test.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 test.services.completion.target;
 
 import 'package:analysis_server/src/services/completion/completion_target.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ skipping 480 matching lines @@
     addTestSource('class C2 {/** */ ^ zoo(z) { } String name; }');
     assertTarget('zoo', 'zoo(z) {}');
   }
 
   test_MethodDeclaration_returnType_afterStarDocComment2() {
     // MethodDeclaration  ClassDeclaration  CompilationUnit
     addTestSource('class C2 {/** */^ zoo(z) { } String name; }');
     assertTarget('zoo', 'zoo(z) {}');
   }
 
+  test_SwitchStatement_c() {
+    // Token('c') SwitchStatement
+    addTestSource('main() { switch(x) {c^} }');
+    assertTarget('}', 'switch (x) {}');
+  }
+
+  test_SwitchStatement_c2() {
+    // Token('c') SwitchStatement
+    addTestSource('main() { switch(x) { c^ } }');
+    assertTarget('}', 'switch (x) {}');
+  }
+
+  test_SwitchStatement_empty() {
+    // SwitchStatement
+    addTestSource('main() { switch(x) {^} }');
+    assertTarget('}', 'switch (x) {}');
+  }
+
+  test_SwitchStatement_empty2() {
+    // SwitchStatement
+    addTestSource('main() { switch(x) { ^ } }');
+    assertTarget('}', 'switch (x) {}');
+  }
+
   test_TypeArgumentList() {
     // TypeName  TypeArgumentList  TypeName
     addTestSource('main() { C<^> c; }');
     assertTarget('', '<>');
   }
 
   test_TypeArgumentList2() {
     // TypeName  TypeArgumentList  TypeName
     addTestSource('main() { C<C^> c; }');
     assertTarget('C', '<C>');
   }
 
   test_VariableDeclaration_lhs_identifier_after() {
     // VariableDeclaration  VariableDeclarationList
     addTestSource('main() {int b^ = 1;}');
     assertTarget('b = 1', 'int b = 1');
   }
 
   test_VariableDeclaration_lhs_identifier_before() {
     // VariableDeclaration  VariableDeclarationList
     addTestSource('main() {int ^b = 1;}');
     assertTarget('b = 1', 'int b = 1');
   }
 }