Integrate EXTRACT_METHOD refactoring into the server.

pkg/analysis_server/test/services/refactoring/extract_method_test.dart

Index: pkg/analysis_server/test/services/refactoring/extract_method_test.dart
diff --git a/pkg/analysis_server/test/services/refactoring/extract_method_test.dart b/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
index 39d38556129dbd334a9659a71d7cb957a192dd0b..e7e6f297e945e6aa59eed12e164dfb58cef117ef 100644
--- a/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/extract_method_test.dart
@@ -376,7 +376,7 @@ main() {
     // update parameters
     return refactoring.checkInitialConditions().then((_) {
       {
-        var parameters = refactoring.parameters.toList();
+        var parameters = _getParametersCopy();
         expect(parameters, hasLength(2));
         parameters[0].name = 'dup';
         parameters[1].name = 'dup';
@@ -400,7 +400,7 @@ main() {
     // update parameters
     return refactoring.checkInitialConditions().then((_) {
       {
-        var parameters = refactoring.parameters.toList();
+        var parameters = _getParametersCopy();
         expect(parameters, hasLength(2));
         parameters[0].name = 'a';
         refactoring.parameters = parameters;
@@ -1563,7 +1563,7 @@ main() {
     // apply refactoring
     return refactoring.checkInitialConditions().then((_) {
       {
-        var parameters = refactoring.parameters.toList();
+        var parameters = _getParametersCopy();
         expect(parameters, hasLength(2));
         expect(parameters[0].name, 'v1');
         expect(parameters[1].name, 'v2');
@@ -1602,7 +1602,7 @@ main() {
     // apply refactoring
     return refactoring.checkInitialConditions().then((_) {
       {
-        var parameters = refactoring.parameters.toList();
+        var parameters = _getParametersCopy();
         expect(parameters, hasLength(2));
         expect(parameters[0].name, 'v1');
         expect(parameters[1].name, 'v2');
@@ -1663,7 +1663,7 @@ main() {
     // apply refactoring
     return refactoring.checkInitialConditions().then((_) {
       {
-        var parameters = refactoring.parameters.toList();
+        var parameters = _getParametersCopy();
         expect(parameters, hasLength(3));
         expect(parameters[0].name, 'v1');
         expect(parameters[1].name, 'v2');
@@ -2303,4 +2303,15 @@ void res() {
     int length = selectionSearch.length;
     _createRefactoring(offset, length);
   }
+
+  /**
+   * Returns a deep copy of [refactoring] parameters.
+   * There was a bug masked by updating parameter instances shared between the
+   * refactoring and the test.
+   */
+  List<RefactoringMethodParameter> _getParametersCopy() {
+    return refactoring.parameters.map((p) {
+      return new RefactoringMethodParameter(p.kind, p.type, p.name, id: p.id);
+    }).toList();
+  }
 }