Normative: Pass correct values to AddDurationToOrSubtractDurationFromPlainTime

This fixes a 'normative typo' introduced in tc39#2166.
Instead of passing temporalTime twice, we need to also pass
temporalDurationLike.

Author: linusg

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>