Bug 1501983 - Add onslotchange event handler.r=smaug

Reflects following spec changes:
- whatwg/html#4129
- whatwg/dom#785

Those new spec addition is already implemented in Safari and Chromium is working on it.

Differential Revision: https://phabricator.services.mozilla.com/D123775

dom/base/ShadowRoot.h

@@ -7,6 +7,7 @@
 #ifndef mozilla_dom_shadowroot_h__
 #define mozilla_dom_shadowroot_h__
 
+#include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/dom/DocumentBinding.h"
 #include "mozilla/dom/DocumentFragment.h"
 #include "mozilla/dom/DocumentOrShadowRoot.h"
@@ -163,6 +164,8 @@ class ShadowRoot final : public DocumentFragment,
   void PartAdded(const Element&);
   void PartRemoved(const Element&);
 
+  IMPL_EVENT_HANDLER(slotchange);
+
   const nsTArray<const Element*>& Parts() const { return mParts; }
 
   const RawServoAuthorStyles* GetServoStyles() const {

dom/events/EventNameList.h

@@ -237,6 +237,7 @@ EVENT(seeked, eSeeked, EventNameType_HTML, eBasicEventClass)
 EVENT(seeking, eSeeking, EventNameType_HTML, eBasicEventClass)
 EVENT(select, eFormSelect, EventNameType_HTMLXUL, eBasicEventClass)
 EVENT(show, eShow, EventNameType_HTML, eBasicEventClass)
+EVENT(slotchange, eSlotChange, EventNameType_All, eBasicEventClass)
 EVENT(stalled, eStalled, EventNameType_HTML, eBasicEventClass)
 EVENT(start, eMarqueeStart, EventNameType_HTMLMarqueeOnly, eBasicEventClass)
 EVENT(submit, eFormSubmit, EventNameType_HTMLXUL, eBasicEventClass)

dom/webidl/EventHandler.webidl

@@ -85,6 +85,7 @@ interface mixin GlobalEventHandlers {
            attribute EventHandler onselect;
            [Pref="dom.menuitem.enabled"]
            attribute EventHandler onshow;
+           attribute EventHandler onslotchange;
            //(Not implemented)attribute EventHandler onsort;
            attribute EventHandler onstalled;
            attribute EventHandler onsubmit;

dom/webidl/ShadowRoot.webidl

@@ -27,6 +27,7 @@ interface ShadowRoot : DocumentFragment
   [Pref="dom.shadowdom.slot.assign.enabled"]
   readonly attribute SlotAssignmentMode slotAssignment;
   readonly attribute Element host;
+  attribute EventHandler onslotchange;
 
   Element? getElementById(DOMString elementId);
 

testing/web-platform/meta/dom/idlharness.window.js.ini

@@ -4,9 +4,6 @@
   [Document interface: existence and properties of interface prototype object's @@unscopables property]
     expected: FAIL
 
-  [ShadowRoot interface: attribute onslotchange]
-    expected: FAIL
-
   [Stringification of document.createNSResolver(document.body)]
     expected: FAIL
 

testing/web-platform/meta/html/dom/idlharness.https.html.ini

@@ -552,9 +552,6 @@ prefs: [dom.security.featurePolicy.experimental.enabled:true, dom.security.featu
   [SVGElement interface: attribute autofocus]
     expected: FAIL
 
-  [SVGElement interface: attribute onslotchange]
-    expected: FAIL
-
   [FormDataEvent interface object length]
     expected: FAIL
 
@@ -750,24 +747,6 @@ prefs: [dom.security.featurePolicy.experimental.enabled:true, dom.security.featu
   [Window interface: attribute oncancel]
     expected: FAIL
 
-  [Document interface: new Document() must inherit property "onslotchange" with the proper type]
-    expected: FAIL
-
-  [Document interface: documentWithHandlers must inherit property "onslotchange" with the proper type]
-    expected: FAIL
-
-  [Window interface: window must inherit property "onslotchange" with the proper type]
-    expected: FAIL
-
-  [Document interface: attribute onslotchange]
-    expected: FAIL
-
-  [Window interface: attribute onslotchange]
-    expected: FAIL
-
-  [Document interface: iframe.contentDocument must inherit property "onslotchange" with the proper type]
-    expected: FAIL
-
   [Window interface: operation print()]
     expected:
       if os == "android": FAIL
@@ -947,12 +926,6 @@ prefs: [dom.security.featurePolicy.experimental.enabled:true, dom.security.featu
   [HTMLElement interface: attribute autofocus]
     expected: FAIL
 
-  [HTMLElement interface: attribute onslotchange]
-    expected: FAIL
-
-  [HTMLElement interface: document.createElement("noscript") must inherit property "onslotchange" with the proper type]
-    expected: FAIL
-
   [HTMLIFrameElement interface: attribute loading]
     expected: FAIL
 

testing/web-platform/meta/html/webappapis/scripting/events/event-handler-all-global-events.html.ini

@@ -22,16 +22,3 @@
 
   [onsecuritypolicyviolation: the content attribute must execute when an event is dispatched]
     expected: FAIL
-
-  [onslotchange: must be on the appropriate locations for GlobalEventHandlers]
-    expected: FAIL
-
-  [onslotchange: the content attribute must be compiled into a function as the corresponding property]
-    expected: FAIL
-
-  [onslotchange: the default value must be null]
-    expected: FAIL
-
-  [onslotchange: the content attribute must execute when an event is dispatched]
-    expected: FAIL
-

testing/web-platform/meta/html/webappapis/scripting/events/event-handler-attributes-body-window.html.ini

@@ -55,13 +55,3 @@
       if not debug and e10s and (os == "linux") and (processor == "x86_64"): FAIL
       if not debug and (os == "mac"): FAIL
       if not debug and (os == "win") and (version == "6.1.7601"): FAIL
-
-  [not shadowed slotchange (window)]
-    expected: FAIL
-
-  [not shadowed slotchange (document.createElement("body"))]
-    expected: FAIL
-
-  [not shadowed slotchange (document.body)]
-    expected: FAIL
-

testing/web-platform/meta/html/webappapis/scripting/events/event-handler-attributes-frameset-window.html.ini

@@ -49,13 +49,3 @@
     disabled: Bug 1485887
     expected:
       if not debug and not webrender and e10s and (os == "linux"): FAIL
-
-  [not shadowed slotchange (window)]
-    expected: FAIL
-
-  [not shadowed slotchange (document.createElement("frameset"))]
-    expected: FAIL
-
-  [not shadowed slotchange (document.body)]
-    expected: FAIL
-

testing/web-platform/meta/html/webappapis/scripting/events/event-handler-attributes-windowless-body.html.ini

@@ -11,9 +11,3 @@
   [securitypolicyviolation is unaffected on a windowless frameset]
     expected: FAIL
 
-  [slotchange is unaffected on a windowless frameset]
-    expected: FAIL
-
-  [slotchange is unaffected on a windowless body]
-    expected: FAIL
-

testing/web-platform/meta/mathml/relations/html5-tree/math-global-event-handlers.tentative.html.ini

@@ -5,24 +5,12 @@
   [oncancel: the default value must be null]
     expected: FAIL
 
-  [onslotchange: the default value must be null]
-    expected: FAIL
-
   [oncancel: the content attribute must be compiled into a function as the corresponding property]
     expected: FAIL
 
-  [onslotchange: dynamic changes on the attribute]
-    expected: FAIL
-
   [oncancel: dispatching an Event at a <math> element must trigger element.oncancel]
     expected: FAIL
 
-  [onslotchange: must be on the appropriate locations for GlobalEventHandlers]
-    expected: FAIL
-
-  [onslotchange: the content attribute must be compiled into a function as the corresponding property]
-    expected: FAIL
-
   [oncancel: must be on the appropriate locations for GlobalEventHandlers]
     expected: FAIL
 
@@ -40,7 +28,3 @@
 
   [onsecuritypolicyviolation: the content attribute must be compiled into a function as the corresponding property]
     expected: FAIL
-
-  [onslotchange: dispatching an Event at a <math> element must trigger element.onslotchange]
-    expected: FAIL
-

widget/EventMessageList.h

@@ -457,6 +457,7 @@ NS_EVENT_MESSAGE(eEditorBeforeInput)
 // selection events
 NS_EVENT_MESSAGE(eSelectStart)
 NS_EVENT_MESSAGE(eSelectionChange)
+NS_EVENT_MESSAGE(eSlotChange)
 
 // visibility change
 NS_EVENT_MESSAGE(eVisibilityChange)

xpcom/ds/StaticAtoms.py

@@ -897,6 +897,7 @@
     Atom("onshippingaddresschange", "onshippingaddresschange"),
     Atom("onshippingoptionchange", "onshippingoptionchange"),
     Atom("onshow", "onshow"),
+    Atom("onslotchange", "onslotchange"),
     Atom("onsqueeze", "onsqueeze"),
     Atom("onsqueezeend", "onsqueezeend"),
     Atom("onsqueezestart", "onsqueezestart"),