[HTML5] Make GDNative support feature-based.

This is suboptimal as it requires adding an extra compile flag, but
rewriting how feature tags work is beyond the scope of this work.

platform/javascript/os_javascript.cpp

@@ -128,12 +128,24 @@ int OS_JavaScript::get_process_id() const {
 }
 
 bool OS_JavaScript::_check_internal_feature_support(const String &p_feature) {
-	if (p_feature == "HTML5" || p_feature == "web")
+	if (p_feature == "HTML5" || p_feature == "web") {
 		return true;
+	}
 
 #ifdef JAVASCRIPT_EVAL_ENABLED
-	if (p_feature == "JavaScript")
+	if (p_feature == "JavaScript") {
 		return true;
+	}
+#endif
+#ifndef NO_THREADS
+	if (p_feature == "threads") {
+		return true;
+	}
+#endif
+#if WASM_GDNATIVE
+	if (p_feature == "wasm32") {
+		return true;
+	}
 #endif
 
 	return false;