Bug 189316

In the following JS:

        "use strict";
        
        class Example {
            get thing() { return 0; }
        }

        const example = new Example();
        example.thing = 1; // TypeError: Attempted to assign to readonly property.
        example = new Example(); // TypeError: Attempted to assign to readonly property.

The same error message appears for both assignments, however the latter should read “TypeError: Attempted to assign to readonly variable.” rather than property.