interceptor is treeshaken over-aggressively

[vsmenon]

The following program:

  void foo() {}

  main() {
    print(foo is Function);
  }

prints "true" on the VM but generates the following error with dart2js:

Uncaught TypeError: Object [object Object] has no method 'getInterceptor'

Adding some explicit dispatch on foo makes the program run correctly. It appears that the is check alone isn't sufficient to keep getInterceptor around but should be.

[kasperl]

Set owner to @johnniwinther.
Added this to the M6 milestone.
Removed Priority-Unassigned label.
Added Priority-High label.

[rakudrama]

Currently the type check is an atomic HInstruction.
If it was decomposed into component parts, one of those parts would be a HInterceptor.
That would solve the problem, and also open up the possibility of interceptor optimizations, see Issue #9732, and customer complaint at Issue #9971.

A short term fix is to register the interceptor call when emitting an is-check.

[rakudrama]

Fixed r24719

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Added Fixed label.