Static fields were broken up from instance fields and demoted to
Stage 2 in the November 2017 TC39 meeting. This patch removes the
test262 tests which test static class fields.

BigInt.parseInt will be removed in
https://github.com/tc39/proposal-bigint/pull/101

This patch removes the associated test262 tests.

The `groups` property must be created unconditionally. https://github.com/tc39/proposal-regexp-named-groups/pull/40

A number of tests for the parsing of the AssignmentExpression production
were expressed using `eval`. This made the tests more complex than
necessary, and also prevented the tests from providing value to
ECMAScript parsers.

Remove the use of `eval` in the relevant tests and instead express the
expectations with literal source text. Remove superfluous "onlyStrict"
restriction from tests by declaring the probe binding prior to
assignment.

A few BigInt tests had a blank line in an inconvenient place which
breaks an old, possibly incorrect YAML parser used by V8's test262
test automation. The best fix is to deploy a new YAML parser, but
in the short term, this patch deletes the blank lines and lets
V8 understand the feature flags below. Related: #1370

Fixes #1355