Normative: Align ArrayBuffer sliceToImmutable length clamping with slice

Ref tc39#1 (comment)

Author: gibson042

spec.emu

@@ -683,9 +683,7 @@ contributors: Mark S. Miller, Richard Gibson
             1. Let _bounds_ be ? ResolveBounds(_len_, _start_, _end_).
             1. Let _first_ be _bounds_.[[From]].
             1. Let _final_ be _bounds_.[[To]].
-            1. Let _newLen_ be _final_ - _first_.
-            1. NOTE: This differs from <emu-xref href="#sec-arraybuffer.prototype.slice" title></emu-xref>, which instead clamps _newLen_ to be non-negative.
-            1. If _newLen_ &lt; 0, throw a *RangeError* exception.
+            1. Let _newLen_ be max(_final_ - _first_, 0).
             1. NOTE: Side-effects of the above steps may have detached or resized _O_.
             1. If IsDetachedBuffer(_O_) is *true*, throw a *TypeError* exception.
             1. Let _fromBuf_ be _O_.[[ArrayBufferData]].