Normative: Fix fraction substring in ParseTimeZoneOffsetString

The fraction variable captures the result of the
TimeZoneUTCOffsetFraction production, which is the two productions
DecimalSeparator and TimeZoneUTCOffsetFractionalPart, meaning that the
result will contain a decimal separator.

When it later appends zeros and gets a substring of the first nine
characters, that separator character is still included and will cause
ToIntegerOrInfinity to return an incorrect result (always 0).

Fix this by changing the substring range to '1 to 10' so the result
doesn't contain the decimal separator and the AO works as expected.

This mistake was already present in the initial revision of the
ParseTimeZoneOffsetString AO when it was added in 01f3c55.

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_ from 0 to 9.
+          1. Let _nanoseconds_ be the String value equal to the substring of _fraction_ from 1 to 10.
           1. Set _nanoseconds_ to ! ToIntegerOrInfinity(_nanoseconds_).
         1. Else,
           1. Let _nanoseconds_ be 0.