Support preallocated pthread & wasm worker from blob

Author: Filip Lundgren

src/library_pthread.js

@@ -98,10 +98,20 @@ var LibraryPThread = {
     },
     initMainThread() {
 #if PTHREAD_POOL_SIZE
-      var pthreadPoolSize = {{{ PTHREAD_POOL_SIZE }}};
-      // Start loading up the Worker pool, if requested.
-      while (pthreadPoolSize--) {
-        PThread.allocateUnusedWorker();
+      preallocateWorkers = () => {
+        var pthreadPoolSize = {{{ PTHREAD_POOL_SIZE }}};
+        // Start loading up the Worker pool, if requested.
+        while (pthreadPoolSize--) {
+         PThread.allocateUnusedWorker();
+        }
+      };
+#if expectToReceiveOnModule('mainScriptUrlOrBlobPromise')
+      if (Module['mainScriptUrlOrBlobPromise']) {
+        Module['mainScriptUrlOrBlobPromise'].then(preallocateWorkers);
+      } else 
+#endif
+      {
+        preallocateWorkers();
       }
 #endif
 #if !MINIMAL_RUNTIME

src/library_wasm_worker.js

@@ -182,7 +182,7 @@ if (ENVIRONMENT_IS_WASM_WORKER
       'mem': wasmMemory,
 #else
       'wasm': wasmModule,
-      'js': Module['mainScriptUrlOrBlob'] || _scriptName,
+      'js': URL.createObjectURL(Module["mainScriptUrlOrBlob"]) || _scriptName,
       'wasmMemory': wasmMemory,
 #endif
       'sb': stackLowestAddress, // sb = stack bottom (lowest stack address, SP points at this when stack is full)