ConversionError and RegExpError tests are methods that existed on
something that preceeded a IE9 Standard. They do not exist in the
specs, at least since ES5.

It's not test262 responsibility to maintain these tests as these
features can be freely implemented by any runtime.

and Number.prototype

Relax test for forbidden extension

Remove unused variables

Update the maintainer to @tcare as @goyakin is no longer maintaining the repo.

Fixes gh-597

Add tests for default parameters

These tests have been re-factored to expand coverage of the "default
parameter" language feature and to more closely adhere to this project's
preferred file organization.

Ensure that when HasBinding of an Object environment record returns an
abrupt completion, that same completion is returned to the runtime.
Update the meta-data of related tests for consistency with this new
test.

Define the expected behavior of new host-defined utilities. These will
facilitate forthcoming tests that concern cross-realm and cross-script
semantics (which are currently untestable using standard ECMAScript
alone).

Due to specs approximation values, some tests are invalid as the harness
helpers rely on another approximated values as Math.LN2.