Editorial: Update substring wording in ParseTimeZoneOffsetString

The phrase "the substring of S from inclusiveStart to exclusiveEnd" is
already well-defined in ECMA-262: https://tc39.es/ecma262/#substring

See also: #1830 (comment)

Author: linusg

spec/timezone.html

@@ -514,7 +514,7 @@ <h1>ParseTimeZoneOffsetString ( _offsetString_ )</h1>
         1. Set _seconds_ to ! ToIntegerOrInfinity(_seconds_).
         1. If _fraction_ is not *undefined*, then
           1. Set _fraction_ to the string-concatenation of the previous value of _fraction_ and the string *"000000000"*.
-          1. Let _nanoseconds_ be the String value equal to the substring of _fraction_ consisting of the code units with indices 0 (inclusive) through 9 (exclusive).
+          1. Let _nanoseconds_ be the String value equal to the substring of _fraction_ from 0 to 9.
           1. Set _nanoseconds_ to ! ToIntegerOrInfinity(_nanoseconds_).
         1. Else,
           1. Let _nanoseconds_ be 0.