Member predicate Impl::MethodCall::getReceiver

Gets the receiver of this method call.

Examples:

foo(42, "bar");    // no receiver
foo.bar(42);       // `foo` is receiver
Foo::bar(foo, 42); // `foo` is receiver
x + y;             // `x` is receiver
-x;                // `x` is receiver
x[y];              // `x` is receiver