Currently, we dispatch keypress event when Enter is pressed without
modifiers or only with the Shift key (line break).
However, other browsers dispatch keypress events for Ctrl + Enter also
even if it doesn't cause any text input.
So, we should fire keypress events for Ctrl + Enter, even in strict
keypress dispatching mode. Note that with other modifiers, it depends on
the browser and/or platform and we can't dispatch the event for
consistent behavior.
This means web developers shouldn't rely one keypress events to catch
Alt + Enter, Meta + Enter and two or more modifiers + Enter.
Based on BZ 1438133
Resolves#2161
* Rename nsIDOMEventTarget::PreHandleEvent to nsIDOMEventTarget::GetEventTargetParent
* Add nsIDOMEventTarget::PreHandleEvent
* Add EventTargetChainItem::GetFirstEventTarget
* Call EventTargetChainItem::PreHandleEvent even it sets mCanHandle=false
* Move form control frame focus/blur from nsGenericHTMLFormElement::GetEventTargetParent to PreHandleEvent
* Move fire change event from HTMLTextAreaElement::GetEventTargetParent to PreHandleEvent
* Refine nsXULElement::GetEventTargetParent
* Move dispatch XUL command from nsXULElement::GetEventTargetParent to PreHandleEvent
* Move fire events and set value from HTMLInputElement::GetEventTargetParent to PreHandleEvent
* Add test case
* Let HTMLInputElement delegate event handling to it's parent class
* Refine EventTargetChain flags to reduce overheads
* Refine event target chain creation
* Refine assertion in EventTargetChainItem::Create
Tag #1375
