Editorial: Simplify ToClampedIndex

spec.html

@@ -5807,19 +5807,15 @@ <h1>
         ToClampedIndex (
           _value_: an ECMAScript language value,
           _length_: a non-negative integer,
-          optional _lowerBound_: an integer,
-          optional _upperBound_: an integer,
         ): either a normal completion containing an integer or a throw completion
       </h1>
       <dl class="header">
         <dt>description</dt>
-        <dd>It converts _value_ to an integer (interpreting negative values relative to _length_) and clamps the result to the inclusive interval from _lowerBound_ to _upperBound_ (respectively defaulting to 0 and _length_).</dd>
+        <dd>It converts _value_ to an integer (interpreting negative values relative to _length_) and clamps the result to the inclusive interval from 0 to _length_.</dd>
       </dl>
       <emu-alg>
-        1. If _lowerBound_ is not present, set _lowerBound_ to 0.
-        1. If _upperBound_ is not present, set _upperBound_ to _length_.
-        1. Assert: _lowerBound_ &le; _upperBound_.
-        1. Return the result of clamping ? ToAbsoluteIndex(_value_, _length_) between _lowerBound_ and _upperBound_.
+        1. Let _index_ be ? ToAbsoluteIndex(_value_, _length_).
+        1. Return the result of clamping _index_ between 0 and _length_.
       </emu-alg>
     </emu-clause>
   </emu-clause>
@@ -37657,7 +37653,8 @@ <h1>Array.prototype.lastIndexOf ( _searchElement_ [ , _fromIndex_ ] )</h1>
           1. Let _O_ be ? ToObject(*this* value).
           1. Let _len_ be ? LengthOfArrayLike(_O_).
           1. If _len_ is 0, return *-1*<sub>𝔽</sub>.
-          1. If _fromIndex_ is not present, let _k_ be _len_ - 1; else let _k_ be ? ToClampedIndex(_fromIndex_, _len_, -1, _len_ - 1).
+          1. If _fromIndex_ is not present, let _k_ be _len_ - 1.
+          1. Else, let _k_ be min(? ToAbsoluteIndex(_fromIndex_, _len_), _len_ - 1).
           1. Repeat, while _k_ &ge; 0,
             1. Let _kPresent_ be ? HasProperty(_O_, ! ToString(𝔽(_k_))).
             1. If _kPresent_ is *true*, then
@@ -39067,7 +39064,8 @@ <h1>%TypedArray%.prototype.lastIndexOf ( _searchElement_ [ , _fromIndex_ ] )</h1
           1. Perform ? ValidateTypedArray(_O_).
           1. Let _len_ be _O_.[[ArrayLength]].
           1. If _len_ is 0, return *-1*<sub>𝔽</sub>.
-          1. If _fromIndex_ is not present, let _k_ be _len_ - 1; else let _k_ be ? ToClampedIndex(_fromIndex_, _len_, -1, _len_ - 1).
+          1. If _fromIndex_ is not present, let _k_ be _len_ - 1.
+          1. Else, let _k_ be min(? ToAbsoluteIndex(_fromIndex_, _len_), _len_ - 1).
           1. Repeat, while _k_ &ge; 0,
             1. Let _kPresent_ be ! HasProperty(_O_, ! ToString(𝔽(_k_))).
             1. If _kPresent_ is *true*, then