Spun off from bug 1503006.

Each patch in this stack deletes comments that are redundant with the new naming convention. In ReadableStreamTee_Cancel, we have a variable named `unwrappedReason` whose purpose is to create a properly wrapped verison of `reason`. It's a little vertiginous. But I think this is what the new convention demands and it's not so bad. Also in ReadableStreamTee_Cancel, step 4.c., we wrap `cancelResult`, which does not have an `unwrapped` tag. This is because we switched realms between the declaration of `cancelResult` and the line of code where we're going to use it. I think this just means the convention is never going to make all correct code obviously-correct and all wrong code obviously-wrong. Still an improvement.

ReportArgTypeError is replaced with a new helper function template, UnwrapAndTypeCheckArgument. The old function used the expression decompiler, but that seems unhelpful here; the new code uses InformalValueTypeName on the actual argument value. Depends on D11683

Depends on D11684

Depends on D11685

Depends on D11687

Pushed by jorendorff@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/9fb1b0aeef48 Part 1: Use the `unwrapped` prefix. Covers spec sections 3.2 to 3.4. r=tcampbell https://hg.mozilla.org/integration/autoland/rev/c87bb95c2447 Part 2: Use the `unwrapped` prefix. Covers spec sections 3.5 to 3.9. r=tcampbell https://hg.mozilla.org/integration/autoland/rev/1918d21eb212 Part 3: Use the `unwrapped` prefix. Covers spec sections 3.10 and 3.12. r=tcampbell https://hg.mozilla.org/integration/autoland/rev/0771df5c7ac5 Part 4: Use the `unwrapped` prefix. Covers spec sections 6.1 to 6.3. r=tcampbell https://hg.mozilla.org/integration/autoland/rev/ca8c304d9bd9 Part 5: Use the `unwrapped` prefix. Covers API entry points. r=tcampbell

https://hg.mozilla.org/mozilla-central/rev/9fb1b0aeef48 https://hg.mozilla.org/mozilla-central/rev/c87bb95c2447 https://hg.mozilla.org/mozilla-central/rev/1918d21eb212 https://hg.mozilla.org/mozilla-central/rev/0771df5c7ac5 https://hg.mozilla.org/mozilla-central/rev/ca8c304d9bd9