Editorial: Fix errors introduced in #2166 (#2179)

* Editorial: Rename AddTemporalPlainYearMonth to AddDurationToOrSubtractDurationFromPlainYearMonth

This AO has both addition and subtraction behavior, based on the first
argument. Update the name accordingly and bring it in line with these
similar AOs:

- AddDurationToOrSubtractDurationFromDuration
- AddDurationToOrSubtractDurationFromInstant
- AddDurationToOrSubtractDurationFromPlainDateTime
- AddDurationToOrSubtractDurationFromPlainTime
- AddDurationToOrSubtractDurationFromZonedDateTime

* Editorial: Fix rendering of 'subtract' in structured header

* Editorial: Pass correct values to AddDurationToOrSubtractDurationFromPlainTime

This fixes a 'normative typo' introduced in #2166.
Instead of passing temporalTime twice, we need to also pass
temporalDurationLike.

spec/plaintime.html

@@ -210,7 +210,7 @@ <h1>Temporal.PlainTime.prototype.add ( _temporalDurationLike_ )</h1>
       <emu-alg>
         1. Let _temporalTime_ be the *this* value.
         1. Perform ? RequireInternalSlot(_temporalTime_, [[InitializedTemporalTime]]).
-        1. Return ? AddDurationToOrSubtractDurationFromPlainTime(~add~, _temporalTime_, _temporalTime_).
+        1. Return ? AddDurationToOrSubtractDurationFromPlainTime(~add~, _temporalTime_, _temporalDurationLike_).
       </emu-alg>
     </emu-clause>
 
@@ -223,7 +223,7 @@ <h1>Temporal.PlainTime.prototype.subtract ( _temporalDurationLike_ )</h1>
       <emu-alg>
         1. Let _temporalTime_ be the *this* value.
         1. Perform ? RequireInternalSlot(_temporalTime_, [[InitializedTemporalTime]]).
-        1. Return ? AddDurationToOrSubtractDurationFromPlainTime(~subtract~, _temporalTime_, _temporalTime_).
+        1. Return ? AddDurationToOrSubtractDurationFromPlainTime(~subtract~, _temporalTime_, _temporalDurationLike_).
       </emu-alg>
     </emu-clause>
 

spec/plainyearmonth.html

@@ -251,7 +251,7 @@ <h1>Temporal.PlainYearMonth.prototype.add ( _temporalDurationLike_ [ , _options_
       <emu-alg>
         1. Let _yearMonth_ be the *this* value.
         1. Perform ? RequireInternalSlot(_yearMonth_, [[InitializedTemporalYearMonth]]).
-        1. Return ? AddTemporalPlainYearMonth(~add~, _yearMonth_, _temporalDurationLike_, _options_).
+        1. Return ? AddDurationToOrSubtractDurationFromPlainYearMonth(~add~, _yearMonth_, _temporalDurationLike_, _options_).
       </emu-alg>
     </emu-clause>
 
@@ -264,7 +264,7 @@ <h1>Temporal.PlainYearMonth.prototype.subtract ( _temporalDurationLike_ [ , _opt
       <emu-alg>
         1. Let _yearMonth_ be the *this* value.
         1. Perform ? RequireInternalSlot(_yearMonth_, [[InitializedTemporalYearMonth]]).
-        1. Return ? AddTemporalPlainYearMonth(~subtract~, _yearMonth_, _temporalDurationLike_, _options_).
+        1. Return ? AddDurationToOrSubtractDurationFromPlainYearMonth(~subtract~, _yearMonth_, _temporalDurationLike_, _options_).
       </emu-alg>
     </emu-clause>
 
@@ -654,10 +654,10 @@ <h1>TemporalYearMonthToString ( _yearMonth_, _showCalendar_ )</h1>
         1. Return _result_.
       </emu-alg>
     </emu-clause>
-    <emu-clause id="sec-temporal-addtemporalplainyearmonth" type="abstract operation">
+    <emu-clause id="sec-temporal-adddurationtoorsubtractdurationfromplainyearmonth" type="abstract operation">
      <h1>
-        AddTemporalPlainYearMonth (
-          _operation_: ~add~ or ~subtract_,
+        AddDurationToOrSubtractDurationFromPlainYearMonth (
+          _operation_: ~add~ or ~subtract~,
           _yearMonth_: a Temporal.PlainYearMonth,
           _temporalDurationLike_: an ECMAScript language value,
           _options_: an ECMAScript language value,