Make it possible to create reasonable subclasses of Event

After this CL, authors can create custom subclasses of Event that actually work
in a reasonable way, including being able to dispatch.

R=hansmuller@google.com, hansmuller@chromium.org

Review URL: https://codereview.chromium.org/938003004

engine/bindings/scripts/templates/interface_dart.template

@@ -11,7 +11,7 @@ part of sky.core;
         {{ '{' if arg.is_named else '[' }}
         {%- endif -%}
         {{ arg.dart_type }} {{ arg.name }}
-        {%- if arg.is_optional %} {{ ':' if arg.is_named else '='}}  {{ arg.dart_default_value }}
+        {%- if arg.is_optional %} {{ ':' if arg.is_named else '='}} {{ arg.dart_default_value }}
         {#- TODO(eseidel): This does not support having both optional and named arguments! -#}
         {%- if loop.last -%}{{ '}' if arg.is_named else ']' }}{%- endif -%}
         {%- endif -%}
@@ -24,7 +24,11 @@ class {{interface_name}} extends {{ parent_interface if parent_interface else 'N
     // Constructors
 {# TODO(eseidel): We only ever have one constructor. #}
 {%- for constructor in constructors %}
-    void _constructor({{ args_macro(constructor.arguments) }}) native "{{interface_name}}_constructorCallback";
+    void _constructor(
+    {%- for arg in constructor.arguments -%}
+        {{ arg.dart_type }} {{ arg.name }}{% if not loop.last %}, {% endif %}
+    {%- endfor -%}
+    ) native "{{interface_name}}_constructorCallback";
     {{interface_name}}({{ args_macro(constructor.arguments) }}) { _constructor(
     {%- for arg in constructor.arguments -%}
         {{ arg.name }}{% if not loop.last %}, {% endif %}

engine/core/events/Event.h

@@ -62,9 +62,9 @@ public:
     // A factory for a simple event. The event doesn't bubble, and isn't
     // cancelable.
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#fire-a-simple-event
-    static PassRefPtr<Event> create(const AtomicString& type)
+    static PassRefPtr<Event> create(const AtomicString& type, bool bubbles = false, bool cancelable = false)
     {
-        return adoptRef(new Event(type, false, false));
+        return adoptRef(new Event(type, bubbles, cancelable));
     }
     static PassRefPtr<Event> createCancelable(const AtomicString& type)
     {

engine/core/events/Event.idl

@@ -18,9 +18,8 @@
  * Boston, MA 02110-1301, USA.
  */
 
-// Introduced in DOM Level 2:
 [
-    EventConstructor,
+    Constructor(DOMString type, [Named] optional boolean bubbles, [Named] optional boolean cancelable),
 ] interface Event {
     // DOM PhaseType
     const unsigned short NONE                = 0;
@@ -38,9 +37,6 @@
 
     void               stopPropagation();
     void               preventDefault();
-    void initEvent([Default=Undefined] optional DOMString eventTypeArg,
-                   [Default=Undefined] optional boolean canBubbleArg,
-                   [Default=Undefined] optional boolean cancelableArg);
 
     // DOM Level 3 Additions.
     readonly attribute boolean defaultPrevented;

tests/events/custom-event-expected.txt

+CONSOLE: unittest-suite-wait-for-done
+CONSOLE: PASS: should be able to dispatch
+CONSOLE: 
+CONSOLE: All 1 tests passed.
+CONSOLE: unittest-suite-success
+DONE

tests/events/custom-event.sky

+<script>
+import "../resources/third_party/unittest/unittest.dart";
+import "../resources/unit.dart";
+
+import "dart:sky";
+
+class MyEvent extends Event {
+  MyEvent() : super("awesome", bubbles: true);
+
+  bool get isCustom => true;
+}
+
+void main() {
+  initUnit();
+
+  test("should be able to dispatch", () {
+    var event = new MyEvent();
+    expect(event.isCustom, isTrue);
+    expect(event.type, equals("awesome"));
+    expect(event.bubbles, isTrue);
+    expect(event.cancelable, isFalse);
+    expect(event.isCustom, isTrue);
+
+    bool gotEvent = false;
+    var element = document.createElement("div");
+    element.addEventListener("awesome", (e) {
+      expect(e, equals(event));
+      expect(event.isCustom, isTrue);
+      gotEvent = true;
+    });
+    element.dispatchEvent(event);
+    expect(gotEvent, isTrue);
+  });
+}
+</script>