Improve coverage for section 13, "Statements and Declarations"

* Re-generate tests

The test generation tool has been modified in the time since these tests
were first generated and committed to the project. Re-generate the tests
using the latest version of the tool.

* Add test cases for Annex B hoisting disqualifiers

The "variable-like" function hoisting semantics defined in Annex B
extension B.3.3 is only applied if "[...] replacing the
FunctionDeclaration f with a VariableStatement that has F as a
BindingIdentifier would not produce any Early Errors [...]". Test262
previously included tests for this condition when the disqualifying
early error originated from the ScriptBody and FunctionBody productions.

Add test cases to assert the behavior when it is disqualified by all
other relevant early errors: Block statements, `for` statements,
`for-of` statements, `for-in` statements, and Switch statements.

* Generate tests

* fixup! Add test cases for Annex B hoisting disqualifiers

* fixup! Add test cases for Annex B hoisting disqualifiers

Correct test case "info" meta-data.

* fixup! Add test cases for Annex B hoisting disqualifiers

Improve test bodies

* fixup! Generate tests

The semantics under test have been incorrectly implemented by the
SpiderMonkey engine.

* Add tests for early errors in functions

* Improve tests for class accessors

Use the `propertyHelper.js` utility in order to functionally test the
property descriptors of class methods.

* Remove redundant tests

The semantics of an IdentifierReference as a PropertyDefinition within
an object initializer are exhaustively tested by the files in this
directory whose name match the pattern `prop-def-id-*.js`.

Delete the redundant tests in favor of the more descriptively-named and
more exhaustive alternatives.

* Rename tests

* Update test names to be more descriptive

* Add tests for property descriptors of accessors

* Add tests for runtime error during method dfn

* Add test for observable iteration

* Extend tests for class "name" inference

Ensure that when a class defines a static "name" method, that method
definition prevents the "name" inference behavior.

* Re-generate tests

* Express JSON syntax tests with multiple assertions

When written with a single assertion, this test verifies only that "one
or more" of the Unicode points produces a SyntaxError. Re-factor the
test so that parsing behavior for each code point can be tested in
isolation.

* Re-introduce assertion

ECMAScript edition 2016 relies on the Unicode standard at version 8.0.0.
As part of a larger effort to update Test262 accordingly, the assertion
for the SyntaxError resulting from the use of the Mongolian Vowel
Separator (U+180E) was removed. However, ECMA-401 (The JSON Data
Interchange Format) continues to describe "insignificant whitespace" as
follows:

> Insignificant  whitespace  is  allowed  before  or  after  any  token.
> The  whitespace  characters  are:  character  tabulation  (U+0009),
> line  feed  (U+000A),  carriage  return (U+000D),  and  space
> (U+0020)

And because ECMA262 specifies step 2 of the `JSON.parse` algorithm as
follows:

> 2. Parse JText interpreted as UTF-16 encoded Unicode points (6.1.4) as
>    a JSON text as specified in ECMA-404. Throw a SyntaxError exception
>    if JText is not a valid JSON text as defined in that specification.

...the use of U+180E between JSON tokens should continue to produce a
SyntaxError, regardless of ECMA262's updated Unicode standard.

* fixup! Express JSON syntax tests with multiple assertions

This is a pure miscellaneous change to use global values of NaN and Infinity instead of their namespaced equivalents.
Ref https://github.com/tc39/test262/pull/690/files/9ae0567a50b4367cf0c692da947ed3613e2e35c3#r69049894
cc @suwc

Fixes gh-683
Ref gh-648
Ref tc39/ecma262#353

Ref. https://hashseed.blogspot.com/2014/08/in-ecma-262-5.html
Ref. https://github.com/tc39/ecma262/pull/300#issuecomment-181376767
Ref. https://github.com/mathiasbynens/regexpu-core/commit/9b10d2a597d4e56b236cae0f9aa2f21a9c6d1122

Fix and add @anba’s U+180E tests

This re-factors some existing Sputnik tests to be more targeted and to use a
pattern that can be generalized to other forms. We could test these all day,
but I've limited myself to forms introduced in ES2015, specifically
YieldExpression and new.target. Note that SpiderMonkey incorrectly throws a
SyntaxError for these.
I thoughtlessly wrote ReferenceError tests for yield = 1 until I realized
that such productions are not actually recognized by the grammar, so the early
errors do not apply. Instead, I've added a negative syntax test for that case.

* Refactor test for valid cover

* Add tests for ValidSimpleAssignmentTarget

Ensure that constructs introduced in ES2015 are disallowed as assignment
targets, with or without a "cover" grammar.

* Add test for grammar precedence of YieldExpression

This changeset increases coverage for section 21, specifically "21.1 String
Objects".

* Add tests for "this" validation of String methods

* Add tests for ToNumber as used by String methods

* Add test for `length` prop of exotic String objs

* fixup! Add test for `length` prop of exotic String objs

Fixes gh-696

As pointed in gh-696, the ArrayBuffer ctor won't throw a RangeError when
invoked without arguments.

Instead of fixing the invalid assertion, this commit removes it as the
coverage for subclassing is already satisfied by the use of slice.

Fixes gh-686

Fixes gh-694

* Improve tests for GeneratorPrototype methods

- Assert return values more consistently
- Expand tests for constraints on `this` value

* Add more tests for dynamic GeneratorFunctions

* Add more tests for GenerationFunction.prototype

* Add more tests for the GeneratorFunction object

* Extend test: GeneratorFunction.prototype.prototype

* Improve precision of tests for generator methods

Extend existing assertions to explicitly verify that execution halts at
the intended location. Correct tests which were previously asserting
this behavior in contexts that did not match their name/description.

* Remove unused variables

* fixup! Improve tests for GeneratorPrototype methods

* fixup! Improve tests for GeneratorPrototype methods

* Add missing test for early error

* Add missing test for WithBaseObject

* Improve coverage for `new.target`

* Add test for deletion of SuperReference

* Add tests for `in` keyword restrictions

* fixup! Improve coverage for `new.target`

The global isNaN is not precise at all, and Number.isNaN is an ES6 feature that makes it preferrable to use assert's sameValue for NaN values, as it handles it internally using the comparison.

This test was intended to assert the semantics of the `for-in`
statement, but it was mistakenly authored to use a `for-of` statement.
Update the statement under test, and improve the testing methodology to
correctly assert the creation of distinct bindings.

Ensure that early errors restricting labelled function declarations
within WithStatement and IfStatement are honored. Rename existing tests
to match the specification's spelling.

The project contains tests for the completion value of most (but not
all) statements. Introduce tests to complete coverage of this detail.

* Improve test coverage for `super` keyword

Add tests for SuperCall and SuperProperty, organized together in the
`test/language/expressions/super/` directory. For SuperProperty, include
tests for usage from within Object initializers and class bodies because
a different set of semantics are observable from each context.

Extend test for HTML comments

The V8 engine incorrectly requires a leading newline character for
MultiLineComments which contain the optional trailing HTMLCloseComment
[1]. Extend the current tests to fail when such an invalid restriction
is in place.
[1] https://bugs.chromium.org/p/v8/issues/detail?id=5142

Switch to non-positional argument.

A subtle aspect of the for-of iteration protocol concerns abrupt
completions that do *not* trigger iterator closing. Although this detail
is implicit in the current structure of the specification text, some
hosts may violate the protocol by closing the iterator because later
steps *do* specify that behavior.

The V8 engine is one such host--as of this writing, it incorrectly
closes the iterator when accessing the `value` property of the iterator
result produces an abrupt completion.

Add tests verifying that the iterator protocol is not violated in this
way for abrupt completions during the semantics of for-of evaluation.