Forward WebDriver CompositionEvent

Dispatch composition events in JS.
Insert characters from composition events to text input.

CompositionEvents currently can only be
created by WebDriver and not by embedders.

components/script/dom/compositionevent.rs

@@ -59,6 +59,10 @@ impl CompositionEvent {
         );
         Ok(event)
     }
+
+    pub fn data(&self) -> &str {
+        &*self.data
+    }
 }
 
 impl CompositionEventMethods for CompositionEvent {

components/script/dom/document.rs

@@ -38,6 +38,7 @@ use crate::dom::bindings::xmlname::{
 };
 use crate::dom::closeevent::CloseEvent;
 use crate::dom::comment::Comment;
+use crate::dom::compositionevent::CompositionEvent;
 use crate::dom::cssstylesheet::CSSStyleSheet;
 use crate::dom::customelementregistry::CustomElementDefinition;
 use crate::dom::customevent::CustomEvent;
@@ -1465,6 +1466,37 @@ impl Document {
         self.window.reflow(ReflowGoal::Full, ReflowReason::KeyEvent);
     }
 
+    pub fn dispatch_composition_event(
+        &self,
+        composition_event: ::keyboard_types::CompositionEvent,
+    ) {
+        // spec: https://w3c.github.io/uievents/#compositionstart
+        // spec: https://w3c.github.io/uievents/#compositionupdate
+        // spec: https://w3c.github.io/uievents/#compositionend
+        // > Event.target : focused element processing the composition
+        let focused = self.get_focused_element();
+        let target = if let Some(elem) = &focused {
+            elem.upcast()
+        } else {
+            // Event is only dispatched if there is a focused element.
+            return;
+        };
+
+        let cancelable = composition_event.state == keyboard_types::CompositionState::Start;
+
+        let compositionevent = CompositionEvent::new(
+            &self.window,
+            DOMString::from(composition_event.state.to_string()),
+            true,
+            cancelable,
+            Some(&self.window),
+            0,
+            DOMString::from(composition_event.data),
+        );
+        let event = compositionevent.upcast::<Event>();
+        event.fire(target);
+    }
+
     // https://dom.spec.whatwg.org/#converting-nodes-into-a-node
     pub fn node_from_nodes_and_strings(
         &self,

components/script/dom/htmlinputelement.rs

@@ -17,6 +17,7 @@ use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::reflector::DomObject;
 use crate::dom::bindings::root::{Dom, DomRoot, LayoutDom, MutNullableDom, RootedReference};
 use crate::dom::bindings::str::DOMString;
+use crate::dom::compositionevent::CompositionEvent;
 use crate::dom::document::Document;
 use crate::dom::element::{
     AttributeMutation, Element, LayoutElementHelpers, RawLayoutElementHelpers,
@@ -1526,6 +1527,23 @@ impl VirtualMethods for HTMLInputElement {
                         &window,
                     );
             }
+        } else if (event.type_() == atom!("compositionstart") ||
+            event.type_() == atom!("compositionupdate") ||
+            event.type_() == atom!("compositionend")) &&
+            self.input_type().is_textual_or_password()
+        {
+            // TODO: Update DOM on start and continue
+            // and generally do proper CompositionEvent handling.
+            if let Some(compositionevent) = event.downcast::<CompositionEvent>() {
+                if event.type_() == atom!("compositionend") {
+                    let _ = self
+                        .textinput
+                        .borrow_mut()
+                        .handle_compositionend(compositionevent);
+                    self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+                }
+                event.mark_as_handled();
+            }
         }
     }
 }

components/script/dom/htmltextareaelement.rs

@@ -13,6 +13,7 @@ use crate::dom::bindings::error::ErrorResult;
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::root::{DomRoot, LayoutDom, MutNullableDom};
 use crate::dom::bindings::str::DOMString;
+use crate::dom::compositionevent::CompositionEvent;
 use crate::dom::document::Document;
 use crate::dom::element::RawLayoutElementHelpers;
 use crate::dom::element::{AttributeMutation, Element};
@@ -576,6 +577,22 @@ impl VirtualMethods for HTMLTextAreaElement {
                         &window,
                     );
             }
+        } else if event.type_() == atom!("compositionstart") ||
+            event.type_() == atom!("compositionupdate") ||
+            event.type_() == atom!("compositionend")
+        {
+            // TODO: Update DOM on start and continue
+            // and generally do proper CompositionEvent handling.
+            if let Some(compositionevent) = event.downcast::<CompositionEvent>() {
+                if event.type_() == atom!("compositionend") {
+                    let _ = self
+                        .textinput
+                        .borrow_mut()
+                        .handle_compositionend(compositionevent);
+                    self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+                }
+                event.mark_as_handled();
+            }
         }
     }