Types for TransitionEvent object

[devversion]

TypeScript Version: Master

Code

/* propertyName and elapsedTime are variables above. */
let event = new TransitionEvent('transitionend', {propertyName, elapsedTime});

As per the definition of the TransitionEvent object, there are no parameters supported (See here)

Expected behavior:

As specified in MDN, the TransitionEvent has a different constructor signature and should accept a type and an options object.

Here is the MDN artice: https://developer.mozilla.org/en-US/docs/Web/API/TransitionEvent/TransitionEvent

Also confirmed that this works the same way in Chrome right now.

Actual behavior:

TypeScript currently only allows us to create a TransitionEvent without any parameters.

Would like to submit a PR if desired and if bug is valid.

[mhegazy]

Should be fixed by #13856

[devversion]

@mhegazy Cool. Thanks!