String couldn't be converted to number by prefix + in the interpolation expression

I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior

In template, {{ +‘1’ + 2 }} will get 12.

Expected behavior

+‘1’ + 2 should get 3 same as JavaScript expression.

Minimal reproduction of the problem with instructions

https://stackblitz.com/edit/angular-e3oqrr?file=app%2Fapp.component.html

What is the motivation / use case for changing the behavior?

Environment

Angular version: X.Y.Z


Browser:
- [ ] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [ ] Firefox version XX
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX
 
For Tooling issues:
- Node version: XX  
- Platform:  

Others:

[trotyl]

PR raised since no reply from OP, suggested tags: type: bug/fix, comp: core & compiler, effort1: easy (hours), freq1: low, severity2: inconvenient, workaround1: obvious.

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