Set correct Function.length on overloaded methods

LayoutTests/fast/js/function-length.html

Index: LayoutTests/fast/js/function-length.html
diff --git a/LayoutTests/fast/js/function-length.html b/LayoutTests/fast/js/function-length.html
index 897f1a4bc85a1d365ad0c877f555fcdd45523f3c..9109b37856d9cf102ccd2ea12d8c747586b02dda 100644
--- a/LayoutTests/fast/js/function-length.html
+++ b/LayoutTests/fast/js/function-length.html
@@ -23,6 +23,13 @@ shouldBe('window.history.length', '1');
 shouldBe('window.URL.createObjectURL.length', '1');
 shouldBe('window.Storage.prototype.key.length', '1');
 
+// One required and one optional argument
+shouldBe('document.importNode.length', '1');
+// One variadic argument
+shouldBe('document.write.length', '0');
+// Overloaded method with varying number of arguments
+shouldBe('CanvasRenderingContext2D.prototype.drawImage.length', '3');
+
 shouldBe('Array.prototype.concat.length', '1');
 shouldBe('Array.prototype.join.length', '1');
 shouldBe('Array.prototype.push.length', '1');