LibJS: Convert most builtin tests to new system

Author: https://github.com/mattco98
Commit: 3f97d75778
Pull-request: https://github.com/SerenityOS/serenity/pull/2689
Reviewed-by: https://github.com/linusg

Libraries/LibJS/Tests/builtins/Number/Number.parseFloat.js

@@ -1,11 +1,5 @@
-load("test-common.js");
-
-try {
+test("basic functionality", () => {
     // Ensuring it's the same function as the global
     // parseFloat() is enough as that already has tests :^)
-    assert(Number.parseFloat === parseFloat);
-
-    console.log("PASS");
-} catch (e) {
-    console.log("FAIL: " + e);
-}
+    expect(Number.parseFloat).toBe(parseFloat);
+});