[rebased] Update tests to match latests drafts

Tests doesn't use async functionality and don't call $DONE, so remove
"async" flag:
- src/params/error/async-gen-named-func-expr.template
- test/language/expressions/async-generator/params-named-dflt-abrupt.js
- test/language/expressions/async-generator/params-named-dflt-ref-later.js
- test/language/expressions/async-generator/params-named-dflt-ref-self.js

Intl.PluralRules.prototype is no longer a Intl.Prototype instance:
- test/intl402/PluralRules/prototype/prototype.js

Intl.PluralRules throws an error when called as a function:
- test/intl402/PluralRules/undefined-newtarget-throws.js

Module namespace objects call OrdinaryDelete for symbol properties:
- test/language/module-code/namespace/internals/delete-non-exported.js

Async generators no longer retrieves "done" property twice:
- src/async-generators/yield-star-async-next.case
- src/async-generators/yield-star-async-return.case
- src/async-generators/yield-star-async-throw.case

Minor units of CLF is 4, so we need to test with maximumFractionDigits=3
to get an error:
- test/intl402/NumberFormat/dft-currency-mnfd-range-check-mxfd.js

DateTimeFormat.prototype.formatToParts length property was changed from
0 to 1:
- test/intl402/DateTimeFormat/prototype/formatToParts/length.js

minimumSignificantDigits and maximumSignificantDigits properties are
only retrieved once:
- test/intl402/NumberFormat/11.1.1_32.js

Closes #948

Fixes for gh-755, per reviews

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

Bug was reported by @anba at
https://github.com/tc39/ecma262/pull/852#issuecomment-291781031

Without this change, you'd expect a RangeError rather than a TypeError.

Corrected typo in annexB templates exsting->existing

Test for the difference between toFixed and toString

Add cases for abrupt completions in yield* in async generator - getIterator

templates for yield star flow

Add cases for abrupt completions in yield* in async generator - next

Add async generator error templates for destructuring binding

Add async generator templates for destructing binding

Add escape-above-astral.js to cover escaping code units as encoded from extended unicode escape. (#942)

Closes #883

Closes #873

* Tests for throwing a TypeError in the TypedArray constructor on a detached buffer

Detached buffer causes an exception
- If it's already detached going into the constructor
- If the byteOffset coercion causes it to be detached

Tests are valid in ES2017

* Test that TypedArray constructor throws when detaching buffer in length calculation

This test is only valid with the PR in https://github.com/tc39/ecma262/pull/852

* Rename files per review

In https://github.com/tc39/ecma262/pull/853 , standard semantics
for this case are proposed. This patch tests the case.

The change is proposed in https://github.com/tc39/ecma262/pull/856
as a fix to https://github.com/tc39/ecma262/issues/855

Here, the ToNumber coercion is done only once, rather than on each
iteration. It does not appear that there were previously any
tests against repeated coercion for this parameter previously.

Tested this test against V8, which failed, as V8 implements the
current spec rather than the proposed one.

Add async-gen templates for params in the test gen tool

Add feature flags for tests on object rest spread

Add async generator templates