There are (at least) 7 places in the spec where 2 adjacent steps are run together:
8.5.4 [[PreventExtensions]] / step 6.
11.2.3 Function Calls / EvaluateMethodCall / step 5
220.127.116.11 Static Semantics / PrototypeMethodDefinitions / group 2 / step 10
18.104.22.168 Object.prototype.toString() / step 2
22.214.171.124 Array.from (...) / step 12
126.96.36.199.2 ArrayIterator.prototype.next() / step 12
B.188.8.131.52 set Object.prototype.__proto__ / step 2
In all but one of these cases, I believe the two steps, once separated, should be sequential steps at the same level as the existing step.
However, in 184.108.40.206.2, I believe the first step should actually be 11.b, i.e. one level deeper, within the previous step.
Also, 220.127.116.11.7 / step 27.c *looks* like two steps run together:
Set srcByteIndex to srcByteIndex + srcElementSize.Return
but I think the "Return" should just be deleted.
(Some overlap with Bug 1811.)
fixed in rev19 editor's draft
fixed in rev19