[Merged by Bors] - Fix RegExp constructor return value when pattern is a regexp

[HalidOdat]

When RegExp constructor is called with a regexp it should return the same regexp, if NewTarget's constructor is the same.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,593	94,593	0
Passed	73,192	73,200	+8
Ignored	17,532	17,532	0
Failed	3,869	3,861	-8
Panics	0	0	0
Conformance	77.38%	77.38%	+0.01%

Fixed tests (10):

test/built-ins/RegExp/S15.10.3.1_A1_T3.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T3.js (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T2.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T2.js (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T1.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T1.js (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T5.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T5.js (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T4.js [strict mode] (previously Failed)
test/built-ins/RegExp/S15.10.3.1_A1_T4.js (previously Failed)

Broken tests (2):

test/built-ins/RegExp/call_with_regexp_match_falsy.js [strict mode] (previously Passed)
test/built-ins/RegExp/call_with_regexp_match_falsy.js (previously Passed)

[codecov]

Codecov Report

Merging #2880 (f817b80) into main (04ddeeb) will increase coverage by 0.01%.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##             main    #2880      +/-   ##
==========================================
+ Coverage   51.22%   51.24%   +0.01%     
==========================================
  Files         427      427              
  Lines       42516    42522       +6     
==========================================
+ Hits        21780    21790      +10     
+ Misses      20736    20732       -4     

Impacted Files	Coverage Δ
boa_engine/src/builtins/regexp/mod.rs	64.06% <80.00%> (+0.22%)	⬆️

... and 3 files with indirect coverage changes

[HalidOdat]

The broken test is caused by an unrelated bug that #2881 fixes

[Razican]

Thanks!

[jedel1043]

Looks good!

bors r+

[bors]

Pull request successfully merged into main.

Build succeeded:

• Build and Test (macos-latest)
• Build and Test (windows-latest)
• Coverage
• Misc