Simplify JS library array literals. NFC (#23925)

Author: sbc100

src/lib/libcore.js

@@ -1505,7 +1505,7 @@ addToLibrary({
   },
 #endif
 
-  $readEmAsmArgsArray: '=[]',
+  $readEmAsmArgsArray: [],
   $readEmAsmArgs__deps: [
     '$readEmAsmArgsArray',
 #if MEMORY64

src/lib/libpthread.js

@@ -947,7 +947,7 @@ var LibraryPThread = {
   },
 
   // Reuse global JS array to avoid creating JS garbage for each proxied call
-  $proxiedJSCallArgs: '=[]',
+  $proxiedJSCallArgs: [],
 
   _emscripten_receive_on_main_thread_js__deps: [
     '$proxyToMainThread',