Fix Function.prototype.toString()

[HalidOdat]

The remaining failing test262 test test/built-ins/Function/prototype/toString/method-computed-property-name.js is failing due to step 2 not being implemented. We fallback to native function to string representation.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	95,574	95,574	0
Passed	75,276	75,340	+64
Ignored	19,482	19,482	0
Failed	816	752	-64
Panics	0	0	0
Conformance	78.76%	78.83%	+0.07%

Fixed tests (64):

test/built-ins/Function/prototype/toString/async-method-class-statement.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-statement.js (previously Failed)
test/built-ins/Function/prototype/toString/async-method-object.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-method-object.js (previously Failed)
test/built-ins/Function/prototype/toString/generator-function-declaration.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/generator-function-declaration.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-object.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-object.js (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-statement-static.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-statement-static.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-method-definition.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-method-definition.js (previously Failed)
test/built-ins/Function/prototype/toString/GeneratorFunction.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/GeneratorFunction.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-bound-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-bound-function.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-generator-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-generator-function.js (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-method-definition.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-method-definition.js (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-expression-static.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-method-class-expression-static.js (previously Failed)
test/built-ins/Function/prototype/toString/async-function-declaration.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-function-declaration.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-arrow-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-arrow-function.js (previously Failed)
test/built-ins/Function/prototype/toString/AsyncGenerator.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/AsyncGenerator.js (previously Failed)
test/built-ins/Function/prototype/toString/async-function-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-function-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-generator-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-generator-function.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-statement.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-statement.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-generator-method-definition.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-generator-method-definition.js (previously Failed)
test/built-ins/Function/prototype/toString/generator-method.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/generator-method.js (previously Failed)
test/built-ins/Function/prototype/toString/generator-function-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/generator-function-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-expression-static.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-expression-static.js (previously Failed)
test/built-ins/Function/prototype/toString/bound-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/bound-function.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-declaration.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-declaration.js (previously Failed)
test/built-ins/Function/prototype/toString/AsyncFunction.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/AsyncFunction.js (previously Failed)
test/built-ins/Function/prototype/toString/async-arrow-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-arrow-function.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-class.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-class.js (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-statement-static.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/async-generator-method-class-statement-static.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-function-expression.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-function-expression.js (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-function.js [strict mode] (previously Failed)
test/built-ins/Function/prototype/toString/proxy-async-function.js (previously Failed)

[codecov]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (f654ad1) 49.49% compared to head (59fd088) 49.49%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3374      +/-   ##
==========================================
- Coverage   49.49%   49.49%   -0.01%     
==========================================
  Files         446      446              
  Lines       43643    43646       +3     
==========================================
+ Hits        21602    21603       +1     
- Misses      22041    22043       +2     

Files	Coverage Δ
boa_engine/src/object/mod.rs	31.57% <0.00%> (-0.08%)	⬇️
boa_engine/src/builtins/function/mod.rs	39.63% <30.00%> (+0.18%)	⬆️

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[Razican]

Good catch! LGTM