Add TypeMirror.isSubtypeOf, TypeMirror.isAssignableTo, ClassMirror.isSubclassOf

sdk/lib/mirrors/mirrors.dart

Index: sdk/lib/mirrors/mirrors.dart
diff --git a/sdk/lib/mirrors/mirrors.dart b/sdk/lib/mirrors/mirrors.dart
index 1c4c799b6037b1d9070c495be354445323df769e..31e4cd3466614b2de387ee19fb2c47550863c23e 100644
--- a/sdk/lib/mirrors/mirrors.dart
+++ b/sdk/lib/mirrors/mirrors.dart
@@ -674,6 +674,20 @@ abstract class TypeMirror implements DeclarationMirror {
    * variables.
    */
   TypeMirror get originalDeclaration;
+
+
+  /**
+   * Checks the subtype relationship, denoted by [:<::] in the language
+   * specification. This is the type relationship used in [:is:] test checks.
+   */
+  bool isSubtypeOf(TypeMirror other);
+
+  /**
+   * Checks the assignability relationship, denoted by [:<=>:] in the language
+   * specification. This is the type relationship tested on assignment in
+   * checked mode.
+   */
+  bool isAssignableTo(TypeMirror other);
 }
 
 /**
@@ -829,6 +843,14 @@ abstract class ClassMirror implements TypeMirror, ObjectMirror {
    * [ArgumentError] is thrown.
    */
   Function operator [](Symbol name);
+
+  /**
+   * Returns whether the class denoted by the receiver is a subclass of the
+   * class denoted by the argument.
+   *
+   * Note that the subclass relationship is reflexive.
+   */
+  bool isSubclassOf(ClassMirror other);
 }
 
 /**