js: support `[export: 'AnotherName']` for FnDecl codegen (#11377)

vlib/builtin/js/builtin.js.v

@@ -5,9 +5,14 @@ pub fn js_throw(s any) {
 	#throw s
 }
 
+# let globalPrint;
+$if js_freestanding {
+	# globalPrint = globalThis.print
+}
+
 pub fn println(s string) {
 	$if js_freestanding {
-		#print(s.str)
+		#globalPrint(s.str)
 	} $else {
 		#console.log(s.str)
 	}
@@ -23,7 +28,7 @@ pub fn print(s string) {
 
 pub fn eprintln(s string) {
 	$if js_freestanding {
-		#print(s.str)
+		#globalPrint(s.str)
 	} $else {
 		#console.error(s.str)
 	}

vlib/v/gen/js/js.v

@@ -1452,7 +1452,14 @@ fn (mut g JsGen) gen_method_decl(it ast.FnDecl, typ FnGenType) {
 
 	g.stmts(it.stmts)
 	g.writeln('}')
-
+	for attr in it.attrs {
+		match attr.name {
+			'export' {
+				g.writeln('globalThis.$attr.arg = ${g.js_name(it.name)};')
+			}
+			else {}
+		}
+	}
 	if is_main {
 		g.write(')();')
 	} else if typ != .struct_method {