[Merged by Bors] - Allow some keywords as identifiers

[tunz]

This PR fixes #2275

There are keywords that are allowed as identifiers.
https://tc39.es/ecma262/#sec-keywords-and-reserved-words

Those that are always allowed as identifiers, but also appear as keywords within certain syntactic productions, at places where Identifier is not allowed: as, async, from, get, meta, of, set, and target.

This PR adds test cases for them, and fixes some cases such as
class A { set(a, b) { } }
function of() { }
let obj = {async: true}
async()

[codecov]

Codecov Report

Merging #2269 (d858f17) into main (90ec460) will increase coverage by 0.12%.
The diff coverage is 29.11%.

@@            Coverage Diff             @@
##             main    #2269      +/-   ##
==========================================
+ Coverage   41.35%   41.48%   +0.12%     
==========================================
  Files         234      234              
  Lines       22019    21987      -32     
==========================================
+ Hits         9107     9121      +14     
+ Misses      12912    12866      -46     

Impacted Files	Coverage Δ
...syntax/parser/statement/iteration/for_statement.rs	37.15% <0.00%> (-2.38%)	⬇️
boa_interner/src/sym.rs	0.00% <ø> (ø)
boa_engine/src/syntax/parser/statement/mod.rs	29.51% <12.50%> (-0.77%)	⬇️
...rser/expression/primary/function_expression/mod.rs	40.90% <20.00%> (-0.56%)	⬇️
...engine/src/syntax/parser/expression/primary/mod.rs	35.40% <25.00%> (-1.39%)	⬇️
.../statement/declaration/hoistable/class_decl/mod.rs	27.25% <40.00%> (+3.33%)	⬆️
...arser/expression/primary/object_initializer/mod.rs	42.44% <50.00%> (+0.64%)	⬆️
...engine/src/syntax/parser/expression/identifiers.rs	33.70% <100.00%> (+3.11%)	⬆️
boa_engine/src/syntax/lexer/template.rs	36.95% <0.00%> (-2.63%)	⬇️
boa_engine/src/builtins/function/mod.rs	22.91% <0.00%> (-0.80%)	⬇️
... and 5 more

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[Razican]

Test262 conformance changes

VM implementation

Test result	main count	PR count	difference
Total	91,733	91,733	0
Passed	64,894	64,910	+16
Ignored	16,580	16,580	0
Failed	10,259	10,243	-16
Panics	0	0	0
Conformance	70.74%	70.76%	+0.02%

Fixed tests (16):

test/built-ins/TypedArray/of/invoked-as-func.js [strict mode] (previously Failed)
test/built-ins/TypedArray/of/invoked-as-func.js (previously Failed)
test/built-ins/TypedArrayConstructors/of/invoked-as-func.js [strict mode] (previously Failed)
test/built-ins/TypedArrayConstructors/of/invoked-as-func.js (previously Failed)
test/built-ins/TypedArrayConstructors/of/BigInt/invoked-as-func.js [strict mode] (previously Failed)
test/built-ins/TypedArrayConstructors/of/BigInt/invoked-as-func.js (previously Failed)
test/language/statements/for-of/head-lhs-async-escaped.js [strict mode] (previously Failed)
test/language/statements/for-of/head-lhs-async-escaped.js (previously Failed)
test/language/statements/for-of/head-lhs-async-parens.js [strict mode] (previously Failed)
test/language/statements/for-of/head-lhs-async-parens.js (previously Failed)
test/language/expressions/division/no-magic-asi.js [strict mode] (previously Failed)
test/language/expressions/division/no-magic-asi.js (previously Failed)
test/language/expressions/division/no-magic-asi-from-block-eval.js [strict mode] (previously Failed)
test/language/expressions/division/no-magic-asi-from-block-eval.js (previously Failed)
test/language/expressions/async-arrow-function/async-lineterminator-identifier-throws.js [strict mode] (previously Failed)
test/language/expressions/async-arrow-function/async-lineterminator-identifier-throws.js (previously Failed)

[Razican]

Thank you for the fix!

I added some comments for potential enhancements. It seems that this test is failing, though:
https://github.com/tc39/test262/blob/f1870753fa616261193b99f79d996889921b3404/test/language/statements/for-of/head-lhs-async-invalid.js

It seems that the async cannot be placed in a for-of. The spec for this is here. It seems it requires a var, a let or a const for it to be valid. This might require changes in the for-of parser.

[Razican]

It seems that the fix for the for...off has broken these tests, that were passing with your previous version:

• https://github.com/tc39/test262/blob/f1870753fa616261193b99f79d996889921b3404/test/language/statements/for-of/head-lhs-async-parens.js
• https://github.com/tc39/test262/blob/f1870753fa616261193b99f79d996889921b3404/test/language/statements/for-of/head-lhs-async-escaped.js

It turns out that the async keyword can be valid in a for...of but only if it's either surrounded with parenthesis or has escaped characters. The "escape characters" information is surely at the lexing level, but we might be missing it, I'm not sure though where is the parenthesis information getting lost.

It's not that critical, since this was broken before, but if you can find a solution that would be perfect :)

[Razican]

It's ready to be merged from my side :) thanks!

[raskad]

Great work!

[raskad]

bors r+

[bors]

Pull request successfully merged into main.

Build succeeded:

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