Please note that some of these tests represent existence, not functionality or full conformance. I hope to test conformance sometime in the future.

IE 7 IE 8 IE 9 IE 10 IE 11 FF 3 FF 3.5, 3.6 FF 4 FF 5 FF 6 FF 7-11 FF 12 FF 28 SF 3.2 SF 4 SF 5 SF 7 WebKit CH 7-10 OP 10.10 OP 10.50-11.10 OP 15 Konq 4.4 Konq 4.9 BESEN Rhino 1.7 Phantom
§function statement Yes Yes Yes Yes Yes Yes Yes Yes[1] Yes[1] Yes[1] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes[2] Yes Yes
§uneval No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§"toSource" method No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes Yes No
§function "name" property No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes
§function "caller" property Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No No Yes
§function "arity" property No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No No No No Yes No
§function "arguments" property Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes
§Function.prototype.isGenerator No No No No No No No No Yes Yes Yes Yes Yes No No No No No No No No No No No No No No
§__proto__ No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes
§__count__ No No No No No Yes Yes No No No No No No No No No No No No No No No No No No No No
§__parent__ No No No No No Yes Yes No No No No No No No No No No No No No No No No No No Yes No
§__noSuchMethod__ No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§__defineGetter__ No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes
§__defineSetter__ No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes
§const No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No Yes
§let No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No No No
§Array generics No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§Expression closures No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No Yes No No
§e4x No No No No No Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No No Yes No
§Sharp variables No No No No No Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No
§RegExp "y" flag No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes No No No No No No No
§RegExp "x" flag No No No No No No No No No No No No No No No No No No No Yes Yes No No No No No No
§RegExp "lastMatch" Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes No Yes Yes
§RegExp.$1-$9 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes
§Callable RegExp No No No No No Yes Yes Yes No No No No No Yes Yes Yes No No Yes Yes Yes No No No No Yes No
§RegExp named groups No No No No No No No No No No No No No No No No No No Yes No Yes No No
§String.prototype.substr Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.trimLeft No No No No No No Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes No No Yes No Yes No No Yes
§String.prototype.trimRight No No No No No No Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes No No Yes No Yes No No Yes
§String.prototype.anchor Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.big Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.bold Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.quote No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No
§String.prototype.replace flags No No No No No Yes No No Yes No
§Object.prototype.watch No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No No No
§Object.prototype.unwatch No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No No No
§Object.prototype.eval No No No No No No No No No No No No No No No No No No No No No No No No Yes No No
§Octal literals Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§error "stack" No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No Yes No Yes Yes No No No No No
§error "lineNumber" No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§error "fileName" No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No Yes No
§error "description" Yes Yes Yes Yes Yes No No No No No No No No No No No No No No No No No No No No No No

[1] From Firefox 4 on, function statements in strict mode functions are only accepted at top level or immediately within another function.

[2] With 'Javascript-specific extensions' option enabled