[HTML5] Refactor JS, threads support, closures.

- Refactored the Engine code, splitted across files.
- Use MODULARIZE option to build emscripten code into it's own closure.
- Enable lto support (saves ~2MiB in release).
- Enable optional closure compiler pass for JS and generated code.
- Enable optional pthreads support.
- Can now build with tools=yes (not much to see yet).
- Dropped some deprecated code for older toolchains.

1 files changed, 3 insertions, 0 deletions

diff --git a/platform/javascript/engine/externs.js b/platform/javascript/engine/externs.js
new file mode 100644
index 0000000000..1a94dd15ec
--- /dev/null
+++ b/platform/javascript/engine/externs.js
@@ -0,0 +1,3 @@
+var Godot;
+var WebAssembly = {};
+WebAssembly.instantiate = function(buffer, imports) {};