Bug 155703

class Foo {
public:
  int operator()() { return 1; }
};

void bar() {
  Foo f;
  f();
}

Action: place the cursor on the parentheses in "f()" and try to navigate using "Go to declaration"

Expected: would recognize that f is an instance of Foo and that the parens refer to the operator(), then allow jumping
to its definition.

Actual: the "Go to declaration" option is grayed out.

Why it matters: some people use coding styles where they extensively overload operators, especially the function call
operator.  When trying to understand code in general, it's helpful to be able to bounce around with the "Go to
declaration".  This is even more helpful when trying to understand code that makes extensive use of operator overloading.