build: narrow TS version to >=2.4.2 and <2.5

[tbosch]

As this is the only version range that we tested against in G3.
We will support newer versions of TypeScript soon
after the Angular 5 release.

Closes #19750

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] angular.io application / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[mary-poppins]

You can preview 5103486 at https://pr19787-5103486.ngbuilds.io/.

[alexeagle]

g3 is on TS 2.5 now, so I'll send a PR to update Angular also

[IgorMinar]

Thanks

…

On Wed, Nov 1, 2017, 7:32 PM Alex Eagle ***@***.***> wrote: g3 is on TS 2.5 now, so I'll send a PR to update Angular also — You are receiving this because your review was requested. Reply to this email directly, view it on GitHub <#19787 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AANM6FKQOXvKQiXpQraOHthhPQY9LtIXks5syLlLgaJpZM4P-GSB> .

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