Why does WebKit run into JavaScript1.7 blocks without supporting any feature of JavaScript 1.7. From the results of my tests, I confirm Safari 3.2 supporting JavaScript 1.6, but testing those language features that make the difference between 1.6 and 1.7 WebKit 528+ fails in each test case. It neither supports block scope variables using the new keyword let nor does it support generators using the new keyword yield nor does it support de structuring assignments. Without implementing these language features, it should not run into javascripts with language="javascript1.7" or type="application/javascript;version=1.7" because those scripts usually make use of exactly those language features not yet implemented in WebKit.
CC'ing some (I hope relevant) people.
This area is a bit of a mess. My understanding is that TC39 has abandoned out-of-band versioning for JavaScript. We execute whatever types the HTML5 spec tells us to execute.
See also: bug 87527.
We now only claim support for https://mimesniff.spec.whatwg.org/#javascript-mime-type.
Actually, this was only very recently fixed. Let's correctly duplicate this to the bug where it was fixed. *** This bug has been marked as a duplicate of bug 257080 ***