test-js: Use prettier and format all files

Author: https://github.com/mattco98
Commit: 6d58c48c2f
Pull-request: https://github.com/SerenityOS/serenity/pull/2689
Reviewed-by: https://github.com/linusg

Libraries/LibJS/Tests/builtins/Date/Date.now.js

@@ -1,10 +1,10 @@
 test("basic functionality", () => {
-    var last = 0;
-    for (var i = 0; i < 100; ++i) {
-        var now = Date.now();
-        expect(now).not.toBeNaN();
-        expect(now).toBeGreaterThan(1580000000000);
-        expect(now).toBeGreaterThanOrEqual(last);
-        last = now;
-    }
+  var last = 0;
+  for (var i = 0; i < 100; ++i) {
+    var now = Date.now();
+    expect(now).not.toBeNaN();
+    expect(now).toBeGreaterThan(1580000000000);
+    expect(now).toBeGreaterThanOrEqual(last);
+    last = now;
+  }
 });