Roll Observatory packages and add a roll script

packages/analyzer/test/src/task/test_support.dart

+// Copyright (c) 2015, 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.src.task.test_support;
+
+import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
+import 'package:analyzer/src/generated/java_engine.dart';
+import 'package:analyzer/task/model.dart';
+
+/**
+ * A configurable analysis task that can be used by tests.
+ */
+class TestAnalysisTask extends AnalysisTask {
+  /**
+   * The descriptor describing this task.
+   */
+  TaskDescriptor descriptor;
+
+  /**
+   * The exception that is to be "thrown" by this task.
+   */
+  CaughtException exception;
+
+  /**
+   * The results whose values are to be provided as outputs from this task.
+   */
+  List<ResultDescriptor> results;
+
+  /**
+   * The next value that is to be used for a result.
+   */
+  int value;
+
+  @override
+  final bool handlesDependencyCycles;
+
+  TestAnalysisTask(AnalysisContext context, AnalysisTarget target,
+      {this.descriptor,
+      this.exception,
+      this.handlesDependencyCycles: false,
+      this.results,
+      this.value: 1})
+      : super(context, target);
+
+  @override
+  String get description => 'Test task';
+
+  @override
+  internalPerform() {
+    if (exception != null) {
+      caughtException = exception;
+    } else if (results != null) {
+      for (ResultDescriptor result in results) {
+        outputs[result] = value++;
+      }
+    } else if (descriptor != null) {
+      for (ResultDescriptor result in descriptor.results) {
+        outputs[result] = value++;
+      }
+    }
+  }
+}