Specifiy MethodMirror.isStatic is terms of whether 'this' is permitted.

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 6d7717bd9eea841ff240f5e3f39fce1b22cba1cb..3275884443ae0058fc912cb2e1a17d166e943922 100644
--- a/sdk/lib/mirrors/mirrors.dart
+++ b/sdk/lib/mirrors/mirrors.dart
@@ -900,10 +900,10 @@ abstract class MethodMirror implements DeclarationMirror {
   List<ParameterMirror> get parameters;
 
   /**
-   * Is the reflectee static?
+   * A function is considered non-static iff it is permited to refer to 'this'.
    *
-   * For the purposes of the mirrors library, a top-level function is
-   * considered static.
+   * Note that generative constructors are considered non-static, whereas
+   * factory constructors are considered static.
    */
   bool get isStatic;