Allow Mojo structs as map keys

mojo/public/interfaces/bindings/tests/test_structs.mojom

Index: mojo/public/interfaces/bindings/tests/test_structs.mojom
diff --git a/mojo/public/interfaces/bindings/tests/test_structs.mojom b/mojo/public/interfaces/bindings/tests/test_structs.mojom
index e3b0aff4c04b295094e029e1065b9845a9f6034d..683f0a56a08fe68fee7ff7b3d901978c97265495 100644
--- a/mojo/public/interfaces/bindings/tests/test_structs.mojom
+++ b/mojo/public/interfaces/bindings/tests/test_structs.mojom
@@ -126,6 +126,8 @@ struct MapKeyTypes {
   map<float, float> f9;
   map<double, double> f10;
   map<string, string> f11;
+  // TODO(tibell): JS/Java don't support struct as key.
+  // map<Rect, Rect> f12;
 };
 
 // Used to verify that various map value types can be encoded and decoded
@@ -386,3 +388,17 @@ struct ContainsInterfaceRequest {
 struct SingleBoolStruct {
   bool value;
 };
+
+// Used to verify that structs containing typemapped types can be hashed (if the
+// typemapped type itself is hashable).
+
+struct ContainsHashable {
+  TypemappedRect rect;
+};
+
+// Used to test that nested structs can be hashed. The nested struct mustn't be
+// nullable.
+
+struct SimpleNestedStruct {
+  ContainsOther nested;
+};