Creates `reflectors`, as a meta-meta feature that enables dynamic selection of a "mirror system".

reflectable/lib/src/encoding_constants.dart

Index: reflectable/lib/src/encoding_constants.dart
diff --git a/reflectable/lib/src/encoding_constants.dart b/reflectable/lib/src/encoding_constants.dart
index 8d9900a9bd1e5559a73707ed423a2212ecd9c269..139dee57283131efe17a00bfc1f1d792e66d36f5 100644
--- a/reflectable/lib/src/encoding_constants.dart
+++ b/reflectable/lib/src/encoding_constants.dart
@@ -16,6 +16,7 @@ const getter = 3;
 const setter = 4;
 const field = 5;
 const parameter = 6;
+const clazz = 7; // Cannot use keyword `class`.
 
 // Flags:
 const staticAttribute = 1 << (flagsBit);
@@ -33,6 +34,7 @@ const classTypeAttribute = 1 << (flagsBit + 11);
 const dynamicReturnTypeAttribute = 1 << (flagsBit + 12);
 const classReturnTypeAttribute = 1 << (flagsBit + 13);
 const voidReturnTypeAttribute = 1 << (flagsBit + 14);
+const enumAttribute = 1 << (flagsBit + 15);
 
 int kindFromEncoding(int encoding) => encoding & ((1 << flagsBit) - 1);