Flatbuffers Merge commit '8cd6f0538a362ceefbcfcbf6c7b8b3f341d1fb41' into master

Upgrade flatbuffers to the latest.

Change-Id: I901787ac6fc5d7ce2c4019cc0d275de68086b4d8
diff --git a/third_party/flatbuffers/js/constants.js b/third_party/flatbuffers/js/constants.js
new file mode 100644
index 0000000..450e2a1
--- /dev/null
+++ b/third_party/flatbuffers/js/constants.js
@@ -0,0 +1,7 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.SIZE_PREFIX_LENGTH = exports.FILE_IDENTIFIER_LENGTH = exports.SIZEOF_INT = exports.SIZEOF_SHORT = void 0;
+exports.SIZEOF_SHORT = 2;
+exports.SIZEOF_INT = 4;
+exports.FILE_IDENTIFIER_LENGTH = 4;
+exports.SIZE_PREFIX_LENGTH = 4;