Remove Value::as_num_to_power()

[HalidOdat]

It changes the following:

• Removed Value::as_num_to_power() this is not spec complaint and Value::pow() should be used instead.
• Added pow operator tests

[codecov]

Codecov Report

Merging #616 into master will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #616      +/-   ##
==========================================
+ Coverage   72.51%   72.60%   +0.08%     
==========================================
  Files         179      179              
  Lines       12553    12566      +13     
==========================================
+ Hits         9103     9123      +20     
+ Misses       3450     3443       -7     

Impacted Files	Coverage Δ
boa/src/builtins/value/mod.rs	66.42% <ø> (+0.93%)	⬆️
boa/src/builtins/value/tests.rs	100.00% <100.00%> (ø)
boa/src/exec/operator/mod.rs	70.32% <0.00%> (+0.64%)	⬆️
boa/src/builtins/value/operations.rs	32.27% <0.00%> (+0.90%)	⬆️

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[github-actions]

Benchmark for 3e8dd03

Click to view benchmark

Test	PR Benchmark	Master Benchmark	%
Arithmetic operations (Execution)	353.6±13.86ns	340.5±16.08ns	+3.85%
Arithmetic operations (Full)	185.7±6.62µs	201.6±10.88µs	-7.89%
Array access (Execution)	7.2±0.42µs	7.3±0.31µs	-1.37%
Array access (Full)	201.0±7.03µs	206.4±10.57µs	-2.62%
Array creation (Execution)	2.9±0.09ms	2.9±0.09ms	0.00%
Array creation (Full)	3.3±0.13ms	3.3±0.08ms	0.00%
Array pop (Execution)	1028.3±36.51µs	1046.0±37.88µs	-1.69%
Array pop (Full)	1372.0±65.50µs	1377.3±63.15µs	-0.38%
Boolean Object Access (Execution)	4.0±0.16µs	3.9±0.13µs	+2.56%
Boolean Object Access (Full)	191.2±5.90µs	194.1±8.06µs	-1.49%
Create Realm	410.0±15.24ns	415.1±14.63ns	-1.23%
Dynamic Object Property Access (Execution)	4.4±0.20µs	4.5±0.26µs	-2.22%
Dynamic Object Property Access (Full)	194.5±8.76µs	199.2±7.60µs	-2.36%
Expression (Lexer)	2.1±0.08µs	2.1±0.10µs	0.00%
Expression (Parser)	5.0±0.19µs	4.7±0.16µs	+6.38%
Fibonacci (Execution)	796.6±28.20µs	783.2±36.75µs	+1.71%
Fibonacci (Full)	1060.3±44.31µs	1014.3±56.87µs	+4.54%
For loop (Execution)	19.6±0.65µs	20.0±0.82µs	-2.00%
For loop (Full)	225.8±8.04µs	215.5±7.10µs	+4.78%
For loop (Lexer)	4.6±0.18µs	4.7±0.18µs	-2.13%
For loop (Parser)	12.5±0.46µs	12.5±0.56µs	0.00%
Goal Symbols (Parser)	7.5±0.29µs	7.4±0.32µs	+1.35%
Hello World (Lexer)	729.3±26.55ns	749.9±27.83ns	-2.75%
Hello World (Parser)	1922.3±86.16ns	1885.6±88.70ns	+1.95%
Long file (Parser)	5.6±0.12ms	5.6±0.16ms	0.00%
Number Object Access (Execution)	3.0±0.18µs	3.1±0.18µs	-3.23%
Number Object Access (Full)	188.7±5.38µs	192.8±11.60µs	-2.13%
Object Creation (Execution)	3.7±0.12µs	3.7±0.12µs	0.00%
Object Creation (Full)	215.6±9.51µs	222.0±10.85µs	-2.88%
RegExp (Execution)	60.5±3.44µs	57.8±2.89µs	+4.67%
RegExp (Full)	291.1±10.69µs	288.7±11.04µs	+0.83%
RegExp Literal (Execution)	60.5±2.55µs	61.0±2.43µs	-0.82%
RegExp Literal (Full)	255.3±9.27µs	263.6±12.38µs	-3.15%
RegExp Literal Creation (Execution)	58.7±2.33µs	56.8±2.20µs	+3.35%
RegExp Literal Creation (Full)	287.9±10.34µs	283.8±8.14µs	+1.44%
Static Object Property Access (Execution)	4.0±0.19µs	3.9±0.15µs	+2.56%
Static Object Property Access (Full)	187.3±5.16µs	194.8±7.88µs	-3.85%
String Object Access (Execution)	5.7±0.29µs	5.7±0.22µs	0.00%
String Object Access (Full)	196.1±17.25µs	194.8±10.14µs	+0.67%
String comparison (Execution)	5.1±0.16µs	5.3±0.21µs	-3.77%
String comparison (Full)	196.0±9.92µs	193.5±8.40µs	+1.29%
String concatenation (Execution)	4.2±0.17µs	4.3±0.11µs	-2.33%
String concatenation (Full)	192.6±9.78µs	193.0±7.96µs	-0.21%
String copy (Execution)	3.1±0.11µs	3.2±0.21µs	-3.13%
String copy (Full)	189.8±8.76µs	188.8±7.16µs	+0.53%
Symbols (Execution)	2.5±0.08µs	2.5±0.11µs	0.00%
Symbols (Full)	189.0±11.42µs	173.5±6.60µs	+8.93%