Add JSON.pm to third_party

third_party/JSON/JSON-2.59/t/00_load.t

Index: third_party/JSON/JSON-2.59/t/00_load.t
diff --git a/third_party/JSON/JSON-2.59/t/00_load.t b/third_party/JSON/JSON-2.59/t/00_load.t
new file mode 100644
index 0000000000000000000000000000000000000000..916c826b15a9ec969e652283bdcca96aa12c4377
--- /dev/null
+++ b/third_party/JSON/JSON-2.59/t/00_load.t
@@ -0,0 +1,15 @@
+use Test::More;
+use strict;
+BEGIN { plan tests => 5 };
+
+BEGIN { $ENV{PERL_JSON_BACKEND} = "JSON::backportPP"; }
+
+BEGIN {
+    use_ok('JSON');
+}
+
+ok( exists $INC{ 'JSON/backportPP.pm' }, 'load backportPP' );
+ok( ! exists $INC{ 'JSON/PP.pm' }, q/didn't load PP/ );
+
+is( JSON->backend, 'JSON::PP' );
+ok( JSON->backend->is_pp );