A Web IDL Constructor extended attribute should be implemented in V8 (bug 65839). We are going to split the patch for bug 65839 into the following eleven steps in order to avoid regressions. This patch is for [5]. Spec: http://www.w3.org/TR/WebIDL/#Constructor [1] "new EventSource()" should throw SYNTAX_ERR when an invalid argument is passed. [2] "new SharedWorker()" should throw SYNTAX_ERR when an invalid argument is passed. [3] "new WebKitCSSMatrix()" should throw SYNTAX_ERR when an invalid argument is passed. [4] "new Worker()" should throw SYNTAX_ERR when an invalid argument is passed. [5] Implement the Web IDL Constructor extended attribute in IDLParser.pm and CodeGeneratorV8.pm. [6] Replace the EventSource constructor in V8 with the Web IDL Constructor extended attribute. [7] Replace the FileReader constructor in V8 with the Web IDL Constructor extended attribute. [8] Replace the SharedWorker constructor in V8 with the Web IDL Constructor extended attribute. [9] Replace the WebKitCSSMatrix constructor in V8 with the Web IDL Constructor extended attribute. [10] Replace the Worker constructor in V8 with the Web IDL Constructor extended attribute. [11] Replace the XSLTProcessor constructor in V8 with the Web IDL Constructor extended attribute. Dependencies: [6][7][8][9][10][11] depends on [1][2][3][4][5]. We can land [1][2][3][4][5] concurrently, and then can land [6][7][8][9][10][11] concurrently.