Editorial: Consolidate static bounds checking in IsValidIntegerIndex …

…and StringGetOwnProperty

Index Numbers with negative sign bit are in the same "not applicable" category as non-integers.

spec.html

@@ -14432,11 +14432,11 @@ <h1>
           1. Let _index_ be CanonicalNumericIndexString(_P_).
           1. If _index_ is *undefined*, return *undefined*.
           1. If _index_ is not an integral Number, return *undefined*.
-          1. If _index_ is *-0*<sub>𝔽</sub>, return *undefined*.
+          1. If _index_ is *-0*<sub>𝔽</sub> or _index_ &lt; *-0*<sub>𝔽</sub>, return *undefined*.
           1. Let _str_ be _S_.[[StringData]].
           1. Assert: _str_ is a String.
           1. Let _len_ be the length of _str_.
-          1. If ℝ(_index_) &lt; 0 or _len_ ≤ ℝ(_index_), return *undefined*.
+          1. If _len_ ≤ ℝ(_index_), return *undefined*.
           1. Let _resultStr_ be the substring of _str_ from ℝ(_index_) to ℝ(_index_) + 1.
           1. Return the PropertyDescriptor { [[Value]]: _resultStr_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
         </emu-alg>
@@ -15057,12 +15057,12 @@ <h1>
         <emu-alg>
           1. If IsDetachedBuffer(_O_.[[ViewedArrayBuffer]]) is *true*, return *false*.
           1. If _index_ is not an integral Number, return *false*.
-          1. If _index_ is *-0*<sub>𝔽</sub>, return *false*.
+          1. If _index_ is *-0*<sub>𝔽</sub> or _index_ &lt; *-0*<sub>𝔽</sub>, return *false*.
           1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_O_, ~unordered~).
           1. NOTE: Bounds checking is not a synchronizing operation when _O_'s backing buffer is a growable SharedArrayBuffer.
           1. If IsTypedArrayOutOfBounds(_taRecord_) is *true*, return *false*.
           1. Let _length_ be TypedArrayLength(_taRecord_).
-          1. If ℝ(_index_) &lt; 0 or ℝ(_index_) ≥ _length_, return *false*.
+          1. If ℝ(_index_) ≥ _length_, return *false*.
           1. Return *true*.
         </emu-alg>
       </emu-clause>