function registerContext(ctx, values) {
      forEach(values, function(v) { PROP_CONTEXTS[v.toLowerCase()] = ctx; });
    }
@ngdoc method
@name $compileProvider#addPropertySecurityContext
@description

Defines the security context for DOM properties bound by ng-prop-*.

@param {string} elementName The element name or '*' to match any element.
@param {string} propertyName The DOM property name.
@param {string} ctx The {@link $sce} security context in which this value is safe for use, e.g. `$sce.URL`
@returns {object} `this` for chaining