Simplify startWorker pthread function. NFC (#24562)

This function doesn't need to take an argument or be declared in closure
externs anymore.

Split out from #24555

Author: sbc100

src/closure-externs/closure-externs.js

@@ -19,12 +19,6 @@ var EMSCRIPTEN$AWAIT;
 // Don't minify createRequire
 var createRequire;
 
-// Don't minify startWorker which we use to start workers once the runtime is ready.
-/**
- * @param {Object} Module
- */
-var startWorker = function(Module) {};
-
 // Closure externs used by library_sockfs.js
 
 /**

src/preamble.js

@@ -144,7 +144,7 @@ function initRuntime() {
 #endif
 
 #if PTHREADS
-  if (ENVIRONMENT_IS_PTHREAD) return startWorker(Module);
+  if (ENVIRONMENT_IS_PTHREAD) return startWorker();
 #endif
 
 #if STACK_OVERFLOW_CHECK >= 2

src/runtime_pthread.js

@@ -20,6 +20,8 @@ var workerID = 0;
 var sharedModules = {};
 #endif
 
+var startWorker;
+
 if (ENVIRONMENT_IS_PTHREAD) {
   // Thread-local guard variable for one-time init of the JS state
   var initializedJS = false;
@@ -58,7 +60,7 @@ if (ENVIRONMENT_IS_PTHREAD) {
         self.onmessage = (e) => messageQueue.push(e);
 
         // And add a callback for when the runtime is initialized.
-        self.startWorker = (instance) => {
+        startWorker = () => {
           // Notify the main thread that this thread has loaded.
           postMessage({ cmd: 'loaded' });
           // Process any messages that were queued before the thread was ready.

src/shell_minimal.js

@@ -127,7 +127,7 @@ function ready() {
 #if PTHREADS
   // This Worker is now ready to host pthreads, tell the main thread we can proceed.
   if (ENVIRONMENT_IS_PTHREAD) {
-    startWorker(Module);
+    startWorker();
   }
 #endif
 }

test/other/codesize/test_codesize_minimal_pthreads.gzsize

@@ -1 +1 @@
-3749
+3744

test/other/codesize/test_codesize_minimal_pthreads.jssize

@@ -1 +1 @@
-7632
+7615

test/other/codesize/test_codesize_minimal_pthreads_memgrowth.gzsize

@@ -1 +1 @@
-3955
+3950

test/other/codesize/test_codesize_minimal_pthreads_memgrowth.jssize

@@ -1 +1 @@
-8063
+8046