Simplify asyncLoad. NFC

Turns out non of the callers were relying the adding of the run
dependencies here.  There are 4 call sites total:

- emscripten_async_wget_data: Explicitly sets noRunDep
- emscripten_wget_data: Explicitly sets noRunDep
- loadDynamicLibrary: The outer loadDylibs already has an explicit calls
  to addRunDependency/removeRunDependency.
- FS_createPreloadedFile: Already has an explicit calls to
  addRunDependency/removeRunDependency.

Author: sbc100

src/library.js

@@ -2181,18 +2181,14 @@ addToLibrary({
     return x.startsWith('dynCall_') ? x : '_' + x;
   },
 
-  $asyncLoad__docs: '/** @param {boolean=} noRunDep */',
-  $asyncLoad: (url, noRunDep) => {
+  $asyncLoad: (url) => {
     return new Promise((resolve, reject) => {
-      var dep = !noRunDep ? getUniqueRunDependency(`al ${url}`) : '';
-      if (dep) addRunDependency(dep);
       readAsync(url).then(
         (arrayBuffer) => {
   #if ASSERTIONS
           assert(arrayBuffer, `Loading data file "${url}" failed (no arrayBuffer).`);
   #endif
           resolve(new Uint8Array(arrayBuffer));
-          if (dep) removeRunDependency(dep);
         }, reject);
     });
   },

src/library_async.js

@@ -471,7 +471,7 @@ addToLibrary({
   emscripten_wget_data: (url, pbuffer, pnum, perror) => {
     return Asyncify.handleSleep((wakeUp) => {
       /* no need for run dependency, this is async but will not do any prepare etc. step */
-      asyncLoad(UTF8ToString(url), /*noRunDep=*/true).then((byteArray) => {
+      asyncLoad(UTF8ToString(url)).then((byteArray) => {
         // can only allocate the buffer after the wakeUp, not during an asyncing
         var buffer = _malloc(byteArray.length); // must be freed by caller!
         HEAPU8.set(byteArray, buffer);

src/library_wget.js

@@ -65,7 +65,7 @@ var LibraryWget = {
   emscripten_async_wget_data: (url, userdata, onload, onerror) => {
     {{{ runtimeKeepalivePush() }}}
     /* no need for run dependency, this is async but will not do any prepare etc. step */
-    asyncLoad(UTF8ToString(url), /*noRunDep=*/true).then((byteArray) => {
+    asyncLoad(UTF8ToString(url)).then((byteArray) => {
       {{{ runtimeKeepalivePop() }}}
       callUserCallback(() => {
         var buffer = _malloc(byteArray.length);

test/other/codesize/test_codesize_hello_dylink.gzsize

@@ -1 +1 @@
-6294
+6276

test/other/codesize/test_codesize_hello_dylink.jssize

@@ -1 +1 @@
-13863
+13831