Auto merge of #14738 - Wafflespeanut:keypress, r=jdm

Properly dispatch keypress event

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This was an attempt to fix #14659. It turned out that the problem wasn't what I thought it was. So, I didn't fix that. On the brighter side, this fixes two related issues.

- Previously, we were unable to launch `keypress` events from `input` and `textarea` elements, because [we'd been cancelling](https://github.com/servo/servo/blob/1327ebd52f53f5f6637a12fab6cf0cad0aa0be6f/components/script/dom/htmlinputelement.rs#L1120-L1124) the key events, so that they don't trigger window navigation - #8400). I've introduced an enum to represent an additional state to an event's cancellation.
- [According to the spec](https://w3c.github.io/uievents/#keypress-event-order), `keypress` (if available) should be dispatched immediately after `keydown`, and it should be followed by `input`. Canceling `keypress` should also cancel `input`. But, we'd been dispatching `input` before `keypress`. We now dispatch `input` once the `keypress` event is on the respective elements.

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

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- [x] These changes do not require tests because it's a refactor?

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r? @jdm or anyone interested

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1 files changed, 28 insertions, 30 deletions

diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 79acb69096d..83dc980716c 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -13,7 +13,6 @@ use dom::bindings::codegen::Bindings::DOMRectBinding::DOMRectMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding;
 use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
 use dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
-use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
 use dom::bindings::codegen::Bindings::EventHandlerBinding::OnErrorEventHandlerNonNull;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
@@ -41,7 +40,7 @@ use dom::documenttype::DocumentType;
 use dom::domimplementation::DOMImplementation;
 use dom::element::{Element, ElementCreator, ElementPerformFullscreenEnter, ElementPerformFullscreenExit};
 use dom::errorevent::ErrorEvent;
-use dom::event::{Event, EventBubbles, EventCancelable};
+use dom::event::{Event, EventBubbles, EventCancelable, EventDefault};
 use dom::eventdispatcher::EventStatus;
 use dom::eventtarget::EventTarget;
 use dom::focusevent::FocusEvent;
@@ -1308,10 +1307,10 @@ impl Document {
                                           props.key_code);
         let event = keyevent.upcast::<Event>();
         event.fire(target);
-        let mut prevented = event.DefaultPrevented();
+        let mut cancel_state = event.get_cancel_state();
 
         // https://w3c.github.io/uievents/#keys-cancelable-keys
-        if state != KeyState::Released && props.is_printable() && !prevented {
+        if state != KeyState::Released && props.is_printable() && cancel_state != EventDefault::Prevented {
             // https://w3c.github.io/uievents/#keypress-event-order
             let event = KeyboardEvent::new(&self.window,
                                            DOMString::from("keypress"),
@@ -1334,40 +1333,39 @@ impl Document {
                                            0);
             let ev = event.upcast::<Event>();
             ev.fire(target);
-            prevented = ev.DefaultPrevented();
-            // TODO: if keypress event is canceled, prevent firing input events
+            cancel_state = ev.get_cancel_state();
         }
 
-        if !prevented {
+        if cancel_state == EventDefault::Allowed {
             constellation.send(ConstellationMsg::SendKeyEvent(ch, key, state, modifiers)).unwrap();
-        }
 
-        // This behavior is unspecced
-        // We are supposed to dispatch synthetic click activation for Space and/or Return,
-        // however *when* we do it is up to us
-        // I'm dispatching it after the key event so the script has a chance to cancel it
-        // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27337
-        match key {
-            Key::Space if !prevented && state == KeyState::Released => {
-                let maybe_elem = target.downcast::<Element>();
-                if let Some(el) = maybe_elem {
-                    synthetic_click_activation(el,
-                                               false,
-                                               false,
-                                               false,
-                                               false,
-                                               ActivationSource::NotFromClick)
+            // This behavior is unspecced
+            // We are supposed to dispatch synthetic click activation for Space and/or Return,
+            // however *when* we do it is up to us.
+            // Here, we're dispatching it after the key event so the script has a chance to cancel it
+            // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27337
+            match key {
+                Key::Space if state == KeyState::Released => {
+                    let maybe_elem = target.downcast::<Element>();
+                    if let Some(el) = maybe_elem {
+                        synthetic_click_activation(el,
+                                                   false,
+                                                   false,
+                                                   false,
+                                                   false,
+                                                   ActivationSource::NotFromClick)
+                    }
                 }
-            }
-            Key::Enter if !prevented && state == KeyState::Released => {
-                let maybe_elem = target.downcast::<Element>();
-                if let Some(el) = maybe_elem {
-                    if let Some(a) = el.as_maybe_activatable() {
-                        a.implicit_submission(ctrl, alt, shift, meta);
+                Key::Enter if state == KeyState::Released => {
+                    let maybe_elem = target.downcast::<Element>();
+                    if let Some(el) = maybe_elem {
+                        if let Some(a) = el.as_maybe_activatable() {
+                            a.implicit_submission(ctrl, alt, shift, meta);
+                        }
                     }
                 }
+                _ => (),
             }
-            _ => (),
         }
 
         self.window.reflow(ReflowGoal::ForDisplay,