Add JS::Object#apply method to call JS function without receiver

This method is similar to `JS::Object#call`, but it is used to call a
function that is not a method of an object.

```ruby
floor = JS.global[:Math][:floor]
floor.apply(3.14) # => 3
JS.global[:Promise].new do |resolve, reject|
  resolve.apply(42)
end.await # => 42
```

Author: kateinoigakukun

packages/gems/js/lib/js.rb

@@ -189,6 +189,20 @@ def respond_to_missing?(sym, include_private)
     self[sym].typeof == "function"
   end
 
+  # Call the receiver (a JavaScript function) with `undefined` as its receiver context. 
+  # This method is similar to JS::Object#call, but it is used to call a function that is not
+  # a method of an object.
+  #   
+  #   floor = JS.global[:Math][:floor]
+  #   floor.apply(3.14) # => 3
+  #   JS.global[:Promise].new do |resolve, reject|
+  #     resolve.apply(42)
+  #   end.await # => 42
+  def apply(*args, &block)
+    args = args + [block] if block
+    JS.global[:Reflect].call(:apply, self, JS::Undefined, args.to_js)
+  end
+
   # Await a JavaScript Promise like `await` in JavaScript.
   # This method looks like a synchronous method, but it actually runs asynchronously using fibers.
   # In other words, the next line to the `await` call at Ruby source will be executed after the

packages/npm-packages/ruby-wasm-wasi/test/unit/test_object.rb

@@ -357,4 +357,13 @@ def test_member_set_with_stress_gc
     JS.global[:tmp] = "1"
     GC.stress = false
   end
+
+  def test_apply
+    object = JS.eval(<<~JS)
+      return { foo(a, b, c) { return a + b + c; } };
+    JS
+    assert_equal 6, object[:foo].apply(1, 2, 3).to_i
+    floor = JS.global[:Math][:floor]
+    assert_equal 3, floor.apply(3.14).to_i
+  end
 end