8.7.{1,2} / alg 1 / step 4.b say:
"Return the result of calling the /get/ internal method
using /base/ as its 'this' value, ..."
(where /get/ is either the standard or special [[Get]] method)
and
"Call the /put/ internal method
using /base/ as its 'this' value, ..."
(where /put/ is either the standard or special [[Put]] method)
This is odd, because the [[Get]] and [[Put]] internal methods don't take a 'this' value. (Note that other invocations of them don't say what to use as a 'this' value.)
The wording used elsewhere that I think applies here is:
"... calling the /get/ internal method on /base/, ..."
"Call the /put/ internal method on /base/, ..."
Note that there's a similar oddity in the preamble to the 'special' versions of [[Get]] and [[Put]].
Oh, and if you make the suggested wording change, then you also need to change the immediately following "and passing" to just "passing".
The "this value" language is trying to deal with the fact that we are essentially do an "apply" of an internal method and we need to indicate what the "this value" for the apply.
I've modified the language in the ES6 draft, but I don't think the current language is sufficiently confusing to both including this issue in the ES5.1 errata.
Fixed in 2015.