Closes #1634.

Add a test covering the behavior of SingleLineHTMLCloseComment where the LineTerminatorSequence within is either Unicode separator code point. (#1612)

- "CannotSuspendMainAgent" feature was changed to "CanBlockIsFalse" flag
- Move annex-b tests into annex-b directory
- Update variable names in nonshared-int-views.js tests
- Move getReport() call in nan-for-timeout.js to avoid iloop
- Update BigInt constructor to match new semantics (tc39/proposal-bigint#138)

Early errors may result from parsing the source text of a test file, but
they may also result from parsing some other source text as referenced
through the ES2015 module syntax. The latter form of early error is not
necessarily detectable by ECMAScript parsers, however. Because of this,
the label "early" is not sufficiently precise for all Test262 consumers
to correctly interpret all tests.

Update the "phase" name of "early" to "parse" for all those negative
tests that describe errors resulting from parsing of the file's source
text directly. A forthcoming commit will update the remaining tests to
use a "phase" name that is more specific to module resolution.

Fixes #1313

Modify $262.uncallableAndIsHTMLDDA() to an optional $262.IsHTMLDDA (whose use must be guarded by a feature of the same name), and narrowly/correctly prescribe its requirements consistent with `document.all`'s behavior in HTML. 

Fix a minor error-message typo, and include the thrown error in the TypeError-testing error message.

Add a test for GetIterator(obj, ~async~) attempting to call obj[@@asyncIterator] even if that value is an object with an [[IsHTMLDDA]] internal slot.

Add tests for the case of <iterator>.return, as used in the iteration protocol, being an object that's uncallable and compares equal to `undefined`.

This pattern makes expectations more explicit by making test files more
literal.

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