For expression of the form (expression == null) and (null == expression), the CPA type inference infers null instead of bool for =='s selector.

Reason: SimpleTypeInferrerVisitor.visitDynamicSend never calls handleDynamicSend when one of the two arguments of == is the literal 'null'. Because of that, getSendReturnType is never called and I never call augmentInferredSelectorType.

Example where it leads to wrong output:

class A {
  operator ==(x) => "a";
}

main() {
  new A() == 1;
  1 == null;
}

Inferred selector type for default inference is Union of [[exact=JSString], [exact=JSBool]]
Inferred selector type for CPA inference is [exact=JSString]
Intersection is [exact=JSString]