Hard to press <BUTTON> in ScrollableView on iPhone/iPad

[ykami]

In test_html-form-controls.html, there are 4 buttons: Button Element, Input Button, Submit Button, and Reset Button. Only "Button Element" is hard to press. The other three buttons do not seem to have this problem.

[ykami]

The "Button Element" button consists of the following tag:

<button>Button Element</button>

When you tap this button on iPhone/iPad, sometimes e.target is the button node, however, sometimes it is the child text node. That is the reason why pressing the button often fails. Other buttons in test_html-form-controls.html are <input> buttons, and thus this problem does not exist.

[ykami]

(In [25573]) Fixes #13281 !strict isFormElement() should check parent node, since the given node may be a child text node of a form element.