[FIX] web: improve perf of matchDomain

`operators` object only contains 3 specific strings as key, and most
domain items are arrays. Checking the type of the item to avoid a costly
and failing `in` check, as well as using direct key access, allows
gaining a lot of time.

The method going from 60ms to 6ms when running the test
"Load 100 recipients at once" on my machine, and the specific line tends
to 0ms.

Part-of: odoo/odoo#145442

addons/web/static/src/core/domain.js

@@ -422,8 +422,8 @@ function matchDomain(record, domain) {
     const reversedDomain = Array.from(domain).reverse();
     const condStack = [];
     for (const item of reversedDomain) {
-        if (item in operators) {
-            const operator = operators[item];
+        const operator = typeof item === "string" && operators[item];
+        if (operator) {
             const operands = condStack.splice(-operator.length);
             condStack.push(operator(...operands));
         } else {