[dart2js] Numeric record type tests give different results at compile time vs. runtime

[fishythefish]

@pragma('dart2js:never-inline')
bool test<T>(dynamic x) => x is T;

void main() {
  print(1 is double);
  print(test<double>(1));

  print((1,) is (double,));
  print(test<(double,)>((1,)));
}

This prints

true
true
false
true

cc @rakudrama @biggs0125

[fishythefish]

Note that the direct is tests are compiled to print(true) and print(false). There's probably a bug here somewhere.

[sigmundch]

Thanks @fishythefish!

BTW - I also came across this when debugging this other issue: #52480

[biggs0125]

I can take a look at this if no one has started digging in yet!