function ThisExpression( node, parents ) {
		var i;
		for ( i = 0; i < parents.length; i++ ) {
			if ( declaresThis( parents[ i ] ) ) {
				return;
			}
		}
		appendUnique( globals, 'this' );
	}
Callback invoked upon encountering a `ThisExpression` AST node.

@private
@param {Node} node - AST node
@param {Array} parents - array of parent AST nodes