Editorial: Remove ToISODayOfYear

ECMA-262 already has a DayWithinYear equation. We had used some handwavy
text in ToISODayOfYear about "the ordinal date in the year according to
ISO-8601" but this change uses the logic already present in the spec.

See: #1641

spec/calendar.html

@@ -464,17 +464,6 @@ <h1>ToISODayOfWeek ( _year_, _month_, _day_ )</h1>
       <emu-note>Monday is 1 and Sunday is 7.</emu-note>
     </emu-clause>
 
-    <emu-clause id="sec-temporal-toisodayofyear" aoid="ToISODayOfYear">
-      <h1>ToISODayOfYear ( _year_, _month_, _day_ )</h1>
-      <emu-alg>
-        1. Assert: _year_ is an integer.
-        1. Assert: _month_ is an integer.
-        1. Assert: _day_ is an integer.
-        1. Let _date_ be the date given by _year_, _month_, and _day_.
-        1. Return _date_'s ordinal date in the year according to ISO-8601 as an integer.
-      </emu-alg>
-    </emu-clause>
-
     <emu-clause id="sec-temporal-toisoweekofyear" aoid="ToISOWeekOfYear">
       <h1>ToISOWeekOfYear ( _year_, _month_, _day_ )</h1>
       <emu-alg>
@@ -989,7 +978,9 @@ <h1>Temporal.Calendar.prototype.dayOfYear ( _temporalDateLike_ )</h1>
         1. Perform ? RequireInternalSlot(_calendar_, [[InitializedTemporalCalendar]]).
         1. Assert: _calendar_.[[Identifier]] is *"iso8601"*.
         1. Let _temporalDate_ be ? ToTemporalDate(_temporalDateLike_).
-        1. Return 𝔽(! ToISODayOfYear(_temporalDate_.[[ISOYear]], _temporalDate_.[[ISOMonth]], _temporalDate_.[[ISODay]])).
+        1. Let _epochDays_ be MakeDay(𝔽(_temporalDate_.[[ISOYear]]), 𝔽(_temporalDate_.[[ISOMonth]] - 1), 𝔽(_temporalDate_.[[ISODay]])).
+        1. Assert: _epochDays_ is finite.
+        1. Return DayWithinYear(MakeDate(_epochDays_, *+0*<sub>𝔽</sub>)).
       </emu-alg>
     </emu-clause>
 

spec/intl.html

@@ -1871,9 +1871,10 @@ <h1>Temporal.Calendar.prototype.dayOfYear ( _temporalDateLike_ )</h1>
             1. Perform ? RequireInternalSlot(_calendar_, [[InitializedTemporalCalendar]]).
             1. Let _temporalDate_ be ? ToTemporalDate(_temporalDateLike_).
             1. If _calendar_.[[Identifier]] is *"iso8601"*, then
-              1. Let _dayOfYear_ be ! ToISODayOfYear(_temporalDate_.[[ISOYear]], _temporalDate_.[[ISOMonth]], _temporalDate_.[[ISODay]]).
-            1. Else,
-              1. Let _dayOfYear_ be ! CalendarDateDayOfYear(_calendar_.[[Identifier]], _temporalDate_).
+              1. Let _epochDays_ be MakeDay(𝔽(_temporalDate_.[[ISOYear]]), 𝔽(_temporalDate_.[[ISOMonth]] - 1), 𝔽(_temporalDate_.[[ISODay]])).
+              1. Assert: _epochDays_ is finite.
+              1. Return DayWithinYear(MakeDate(_epochDays_, *+0*<sub>𝔽</sub>)).
+            1. Let _dayOfYear_ be ! CalendarDateDayOfYear(_calendar_.[[Identifier]], _temporalDate_).
             1. Return 𝔽(_dayOfYear_).
           </emu-alg>
         </emu-clause>