Update LKG to enable improved narrowing in 4.4.

[DanielRosenwasser]

Fixes #44841.

[DanielRosenwasser]

This one is actually unfortunate - pendingExpressions is actually typed as never because we have an earlier assignment of undefined followed by a check for some(...) which is a type predicate on readonly T[]. Since you can't narrow down a readonly T[] from an undefined, it leaves us with never.

The real culprit is #9998, but it is also strange that we just allow a spread of type never.

[DanielRosenwasser]

I did notice one opportunity for a new narrowing: accessing a property on a non-null value.

When you write

if (foo!.bar) {
    // ...
}

You shouldn't have to repeat the foo! within the if since you'll have crashed by that point. In a sense, it's an implicit assertion on foo.

if (foo!.bar) {
  foo.bar.baz()
}

I think the only downside is that it's sometimes nice to ensure all uses of a variable look similar.

[sandersn]

How did you find all the places to remove !? Did the linter point them out for you?

[DanielRosenwasser]

At first it was manual just to get a sense of some patterns it would/wouldn't catch, but then yes, I ran gulp lint --fix.

[OpportunityLiu]

Why this is changed to Evnet from HashChangeEvent?

[DanielRosenwasser]

These are auto-generated, so they might need to be fixed up. Maybe @saschanaz or @orta have more context here.

[orta]

This got added back: microsoft/TypeScript-DOM-lib-generator#1104

[buschtoens]

These properties used to be available on SVGElement, which used to extend SVGElementInstance in LOC 12903. They disappeared during the upgrade from v4.3.5 to v4.4.2.

Reported here: microsoft/TypeScript-DOM-lib-generator#1023 (comment)

[buschtoens]

Removal was intentional, as per microsoft/TypeScript-DOM-lib-generator#1023 (comment):

Those are not available on any modern browser nor MDN, and thus are probably IE-specific properties. The removal is intended since the types library intends to only include things that exist in modern browsers.