Remove unused calledMain global. NFC (#17478)

This was only used by `proxyWorker.js` so move it there and use the
existing `postRun` mechanism to set it.

The motivation for this change is that it simplifies `callMain` in a
way that should allow us to use `callUserCallback` there rather than
the current/local try/catch.

`calledMain` is not references anywhere else in the codebase or in any
documentation so I think removing it should be safe.

Author: sbc100

ChangeLog.md

@@ -24,6 +24,8 @@ See docs/process.md for more on how version tagging works.
   removed (and replaced with an assert) as it had no uses internally and was
   removed (and replaced with an assert) as it had now uses internally and was
   untested.
+- Removed unused `calledMain` global variable from the JS runtime.  Folks who
+  want to know when main is done can use `Module[postRun]`.
 
 3.1.16 - 07/14/2022
 -------------------

src/postamble.js

@@ -92,8 +92,6 @@ function runMemoryInitializer() {
 
 var calledRun;
 
-var calledMain = false;
-
 #if STANDALONE_WASM && MAIN_READS_PARAMS
 var mainArgs = undefined;
 #endif
@@ -189,8 +187,6 @@ function callMain(args) {
     return handleException(e);
 #endif // !PROXY_TO_PTHREAD
   } finally {
-    calledMain = true;
-
 #if ABORT_ON_WASM_EXCEPTIONS
     // See abortWrapperDepth in preamble.js!
     abortWrapperDepth -= 2;

src/proxyWorker.js

@@ -395,6 +395,12 @@ if (!ENVIRONMENT_IS_PTHREAD) {
 
 var messageBuffer = null;
 var messageResenderTimeout = null;
+var calledMain = false;
+
+// Set calledMain to true during postRun which happens onces main returns
+if (!Module['postRun']) Module['postRun'] = [];
+if (typeof Module['postRun'] == 'function') Module['postRun'] = [Module['postRun']];
+Module['postRun'].push(() => { calledMain = true; });
 
 function messageResender() {
   if (calledMain) {

tests/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-84065
+84016

tests/other/test_unoptimized_code_size_no_asserts.js.size

@@ -1 +1 @@
-56607
+56558

tests/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-66130
+66081