Add tests for Event.returnValue

[cvrebert]

Refs whatwg/dom#334
This assumes that Event.returnValue = false is spec'd as equivalent to Event.preventDefault(), with Event.returnValue = true spec'd as a no-op.

[wpt-pr-bot]

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[wpt-stability-bot]

Firefox

Testing revision 7cd5c05
Starting 10 test iterations
All results were stable

All results

/dom/events/Event-initEvent.html

Subtest	Results
	OK
Properties of initEvent(type, true, false)	FAIL
Calling initEvent during propagation.	PASS
Properties of initEvent(type, false, true)	FAIL
Calling initEvent must unset the stop immediate propagation flag.	PASS
Calling initEvent must unset the stop propagation flag.	PASS
Calling initEvent multiple times (getting type).	PASS
Calling initEvent multiple times (not getting type).	PASS
Properties of initEvent(type, true, true)	FAIL
Properties of initEvent(type, false, false)	FAIL
Calling initEvent must not have an effect during dispatching.	PASS

/dom/events/AddEventListenerOptions-passive.html

Subtest	Results
	OK
passive behavior of one listener should be unaffected by the presence of other listeners	PASS
Equivalence of option values	PASS
Supports passive option on addEventListener only	PASS
returnValue should be ignored if-and-only-if the passive option is true	FAIL
preventDefault should be ignored if-and-only-if the passive option is true	PASS

/dom/events/Event-defaultPrevented-after-dispatch.html

Subtest	Results
	OK
Default prevention via returnValue	FAIL
Default prevention via preventDefault	PASS

/dom/events/Event-returnValue.html

Subtest	Results
	OK
preventDefault() should change returnValue if cancelable is true.	FAIL
preventDefault() should not change returnValue if cancelable is false.	FAIL
When an event is created, returnValue should be initialized to true.	FAIL
returnValue=false should have no effect if cancelable is false.	FAIL
initEvent should unset returnValue.	FAIL
returnValue should change returnValue if cancelable is true.	FAIL
initEvent should work correctly (cancelable).	FAIL
returnValue=true should have no effect.	FAIL
initEvent should work correctly (not cancelable).	FAIL

/dom/events/EventTarget-dispatchEvent-returnvalue.html

Subtest	Results
	OK
Return value of EventTarget.dispatchEvent() affected by preventDefault().	FAIL
Return value of EventTarget.dispatchEvent() affected by returnValue.	FAIL

/dom/events/Event-dispatch-click.html

Subtest	Results
	OK
event state during post-click handling	FAIL
redispatch during post-click handling	FAIL
disabled checkbox still has activation behavior	PASS
pick the first with activation behavior <a href>	FAIL
disconnected radio should be checked	FAIL
disconnected form should not submit	PASS
basic with wrong event class	PASS
disabled checkbox still has activation behavior, part 2	FAIL
pick the first with activation behavior <input type=checkbox>	FAIL
disconnected checkbox should be checked	FAIL
look at parents when event bubbles	PASS
look at parents only when event bubbles	FAIL
basic with click()	PASS
basic with dispatchEvent()	PASS

/dom/events/Event-defaultPrevented.html

Subtest	Results
	OK
returnValue should not change defaultPrevented if cancelable is false.	PASS
returnValue should change defaultPrevented if cancelable is true.	PASS
When an event is created, defaultPrevented should be initialized to false.	PASS
preventDefault() should not change defaultPrevented if cancelable is false.	PASS
preventDefault() should change defaultPrevented if cancelable is true.	PASS
initEvent should work correctly (cancelable).	PASS
initEvent should unset defaultPrevented.	PASS
initEvent should work correctly (not cancelable).	PASS

/dom/events/Event-constructors.html

Subtest	Results
	OK
Event constructors 11	PASS
Event constructors 10	PASS
Event constructors	PASS
Event constructors 3	FAIL
Event constructors 2	FAIL
Event constructors 1	PASS
Event constructors 7	PASS
Event constructors 6	PASS
Event constructors 5	PASS
Event constructors 4	PASS
Event constructors 9	PASS
Event constructors 8	PASS
Event constructors 12	PASS

[wpt-stability-bot]

Chrome

Testing revision 7cd5c05
Starting 10 test iterations
All results were stable

All results

/dom/events/Event-initEvent.html

Subtest	Results
	OK
Properties of initEvent(type, true, false)	PASS
Calling initEvent during propagation.	PASS
Properties of initEvent(type, false, true)	PASS
Calling initEvent must unset the stop immediate propagation flag.	PASS
Calling initEvent must unset the stop propagation flag.	PASS
Calling initEvent multiple times (getting type).	PASS
Calling initEvent multiple times (not getting type).	PASS
Properties of initEvent(type, true, true)	PASS
Properties of initEvent(type, false, false)	PASS
Calling initEvent must not have an effect during dispatching.	PASS

/dom/events/AddEventListenerOptions-passive.html

Subtest	Results
	ERROR
passive behavior of one listener should be unaffected by the presence of other listeners	FAIL
Equivalence of option values	PASS
Supports passive option on addEventListener only	PASS
returnValue should be ignored if-and-only-if the passive option is true	FAIL
preventDefault should be ignored if-and-only-if the passive option is true	PASS

/dom/events/Event-defaultPrevented-after-dispatch.html

Subtest	Results
	OK
Default prevention via returnValue	PASS
Default prevention via preventDefault	PASS

/dom/events/Event-returnValue.html

Subtest	Results
	OK
preventDefault() should change returnValue if cancelable is true.	FAIL
preventDefault() should not change returnValue if cancelable is false.	PASS
When an event is created, returnValue should be initialized to true.	PASS
returnValue=false should have no effect if cancelable is false.	FAIL
initEvent should unset returnValue.	PASS
returnValue should change returnValue if cancelable is true.	FAIL
initEvent should work correctly (cancelable).	PASS
returnValue=true should have no effect.	FAIL
initEvent should work correctly (not cancelable).	PASS

/dom/events/EventTarget-dispatchEvent-returnvalue.html

Subtest	Results
	OK
Return value of EventTarget.dispatchEvent() affected by preventDefault().	PASS
Return value of EventTarget.dispatchEvent() affected by returnValue.	PASS

/dom/events/Event-dispatch-click.html

Subtest	Results
	OK
event state during post-click handling	PASS
redispatch during post-click handling	PASS
disabled checkbox still has activation behavior	PASS
pick the first with activation behavior <a href>	PASS
disconnected radio should be checked	PASS
disconnected form should not submit	FAIL
basic with wrong event class	PASS
disabled checkbox still has activation behavior, part 2	PASS
pick the first with activation behavior <input type=checkbox>	FAIL
disconnected checkbox should be checked	PASS
look at parents when event bubbles	FAIL
look at parents only when event bubbles	PASS
basic with click()	PASS
basic with dispatchEvent()	PASS

/dom/events/Event-defaultPrevented.html

Subtest	Results
	OK
returnValue should not change defaultPrevented if cancelable is false.	FAIL
returnValue should change defaultPrevented if cancelable is true.	PASS
When an event is created, defaultPrevented should be initialized to false.	PASS
preventDefault() should not change defaultPrevented if cancelable is false.	PASS
preventDefault() should change defaultPrevented if cancelable is true.	PASS
initEvent should work correctly (cancelable).	PASS
initEvent should unset defaultPrevented.	PASS
initEvent should work correctly (not cancelable).	PASS

/dom/events/Event-constructors.html

Subtest	Results
	OK
Event constructors 11	PASS
Event constructors 10	PASS
Event constructors	PASS
Event constructors 3	PASS
Event constructors 2	PASS
Event constructors 1	PASS
Event constructors 7	PASS
Event constructors 6	PASS
Event constructors 5	PASS
Event constructors 4	PASS
Event constructors 9	PASS
Event constructors 8	PASS
Event constructors 12	PASS

[miketaylr]

I cherry-picked these two commits (fixing up the comma fix into the first) into #4790, so let's close this one and continue review in #4790.