LibJS: Add spec comments to Value::to_u8_clamp()

Author: https://github.com/linusg
Commit: 34e372cbff
Pull-request: https://github.com/SerenityOS/serenity/pull/16405
Reviewed-by: https://github.com/davidot ✅

Userland/Libraries/LibJS/Runtime/Value.cpp

@@ -1033,21 +1033,39 @@ ThrowCompletionOr<u8> Value::to_u8(VM& vm) const
 // 7.1.12 ToUint8Clamp ( argument ), https://tc39.es/ecma262/#sec-touint8clamp
 ThrowCompletionOr<u8> Value::to_u8_clamp(VM& vm) const
 {
+    // 1. Let number be ? ToNumber(argument).
     auto number = TRY(to_number(vm));
+
+    // 2. If number is NaN, return +0𝔽.
     if (number.is_nan())
         return 0;
+
     double value = number.as_double();
+
+    // 3. If ℝ(number) ≤ 0, return +0𝔽.
     if (value <= 0.0)
         return 0;
+
+    // 4. If ℝ(number) ≥ 255, return 255𝔽.
     if (value >= 255.0)
         return 255;
+
+    // 5. Let f be floor(ℝ(number)).
     auto int_val = floor(value);
+
+    // 6. If f + 0.5 < ℝ(number), return 𝔽(f + 1).
     if (int_val + 0.5 < value)
         return static_cast<u8>(int_val + 1.0);
+
+    // 7. If ℝ(number) < f + 0.5, return 𝔽(f).
     if (value < int_val + 0.5)
         return static_cast<u8>(int_val);
+
+    // 8. If f is odd, return 𝔽(f + 1).
     if (fmod(int_val, 2.0) == 1.0)
         return static_cast<u8>(int_val + 1.0);
+
+    // 9. Return 𝔽(f).
     return static_cast<u8>(int_val);
 }