tests/cases/compiler/unknownSymbolOffContextualType1.ts(16,18): error TS2339: Property 'xyxyxyx' does not exist on type 'HTMLElement'.


==== tests/cases/compiler/unknownSymbolOffContextualType1.ts (1 errors) ====
    declare var document: Document;
    interface Document {
        getElementById(elementId: string): HTMLElement;
    }
    interface HTMLElement {
        isDisabled: boolean;
    }
    function getMaxWidth(elementNames: string[]) {
        var elements = elementNames.map(function (name) {
            return document.getElementById(name);
        });
        var enabled = elements.filter(function (e) {
            return !e.isDisabled;
        });
        var widths = enabled.map(function (e) {
            return e.xyxyxyx;  // error expected here
                     ~~~~~~~
!!! error TS2339: Property 'xyxyxyx' does not exist on type 'HTMLElement'.
        });
        var maxWidth = widths.reduce(function (a, b) {
            return a > b ? a : b;
        });
        return maxWidth;
    }
    