Move ParameterKind so it can be used in the element model

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/utilities/dart/ParameterKind.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/utilities/dart/ParameterKind.java
===================================================================
--- editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/utilities/dart/ParameterKind.java	(revision 0)
+++ editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/utilities/dart/ParameterKind.java	(revision 0)
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2012, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.google.dart.engine.utilities.dart;
+
+/**
+ * The enumeration {@code ParameterKind} defines the different kinds of parameters. There are two
+ * basic kinds of parameters: required and optional. Optional parameters are further divided into
+ * two kinds: positional optional and named optional.
+ */
+public enum ParameterKind {
+  REQUIRED(false),
+  POSITIONAL(true),
+  NAMED(true);
+
+  /**
+   * A flag indicating whether this is an optional parameter.
+   */
+  private boolean isOptional;
+
+  /**
+   * Initialize a newly created kind with the given state.
+   * 
+   * @param isOptional {@code true} if this is an optional parameter
+   */
+  private ParameterKind(boolean isOptional) {
+    this.isOptional = isOptional;
+  }
+
+  /**
+   * Return {@code true} if this is an optional parameter.
+   * 
+   * @return {@code true} if this is an optional parameter
+   */
+  public boolean isOptional() {
+    return isOptional;
+  }
+}