Attempt to fix wrong canvas size

After bumping emsdk version, the canvas loads with an invalid size. This
commit attempts to fix this.

README.md

@@ -11,9 +11,9 @@ build to [jumpartifact.com/demo0](https://jumpartifact.com/demo0/).
 Clone `https://github.com/emscripten-core/emsdk.git` to `${HOME}/git/emsdk`, and
 run the following commands in the cloned directory:
 
-    git checkout 3.1.50
-    ./emsdk install 3.1.50
-    ./emsdk activate 3.1.50
+    git checkout 3.1.56
+    ./emsdk install 3.1.56
+    ./emsdk activate 3.1.56
 
 Now you can use emsdk by sourcing the `emsdk_env.sh` file and using emcc/em++.
 The Makefile in `wasm_build/` should now "just work" with `make`.

emsdk_version

@@ -1 +1 @@
-3.1.50
+3.1.56

src/main.cc

@@ -57,7 +57,11 @@ void jumpartifact_demo_update(void *ud) {
 }
 
 int main() {
+#ifdef __EMSCRIPTEN__
+  InitWindow(call_js_get_canvas_width(), call_js_get_canvas_height(), "Demo");
+#else
   InitWindow(800, 800, "Demo");
+#endif
 
 #ifdef NDEBUG
   SetTraceLogLevel(LOG_WARNING);