158062 2016-05-25 02:39:59 -0700 "use strict"; delete ProgressEvent.length; should not throw 2016-05-25 07:47:07 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified RESOLVED DUPLICATE 145460 P2 Normal --- 1 zcorpan webkit-unassigned mark.lam saam ysuzuki oldest_to_newest 1196255 0 zcorpan 2016-05-25 02:39:59 -0700 See https://github.com/w3c/web-platform-tests/pull/3068 This fails in WebKit: <!DOCTYPE html> <script> "use strict"; try { delete ProgressEvent.length; w('PASS'); } catch(e) { w('FAIL'); } </script> http://software.hixie.ch/utilities/js/live-dom-viewer/saved/4231 Per ES6 deleting a function's "length" property should apparently not throw (even in strict mode). It throws in WebKit for a vanilla function: <!DOCTYPE html> <script> "use strict"; var x = function(x) {}; try { delete x.length; w('PASS'); } catch(e) { w('FAIL'); } </script> http://software.hixie.ch/utilities/js/live-dom-viewer/saved/4232 Also, the ProgressEvent interface object is typeof "object" in WebKit but per WebIDL should be "function". <!DOCTYPE html> <script> w(typeof ProgressEvent == "function" ? "PASS" : "FAIL"); </script> http://software.hixie.ch/utilities/js/live-dom-viewer/saved/4233 1196258 1 zcorpan 2016-05-25 03:08:19 -0700 Or, this should be true: Object.getOwnPropertyDescriptor(function(){}, 'length').configurable It seems this bug is a dup of the following two bugs: https://bugs.webkit.org/show_bug.cgi?id=124598 https://bugs.webkit.org/show_bug.cgi?id=145460 *** This bug has been marked as a duplicate of bug 145460 ***