LibJS/JIT: Add builtin for Math.floor()

Author: https://github.com/awesomekling
Commit: 08590adf40
Pull-request: https://github.com/SerenityOS/serenity/pull/22041
Reviewed-by: https://github.com/skyrising

Userland/Libraries/LibJS/Runtime/MathObject.h

@@ -21,6 +21,7 @@ public:
     static ThrowCompletionOr<Value> log_impl(VM&, Value);
     static ThrowCompletionOr<Value> sqrt_impl(VM&, Value);
     static ThrowCompletionOr<Value> pow_impl(VM&, Value base, Value exponent);
+    static ThrowCompletionOr<Value> floor_impl(VM&, Value);
 
 private:
     explicit MathObject(Realm&);