Fix usage of ES.CalendarEquals (#75)

Port of tc39/proposal-temporal#1858

Author: justingrant

lib/plaindate.ts

@@ -268,7 +268,7 @@ export class PlainDate implements Temporal.PlainDate {
       const val2 = GetSlot(other, slot);
       if (val1 !== val2) return false;
     }
-    return ES.CalendarEquals(this, other);
+    return ES.CalendarEquals(GetSlot(this, CALENDAR), GetSlot(other, CALENDAR));
   }
   toString(options = undefined) {
     if (!ES.IsTemporalDate(this)) throw new TypeError('invalid receiver');

lib/plaindatetime.ts

@@ -594,7 +594,7 @@ export class PlainDateTime implements Temporal.PlainDateTime {
       const val2 = GetSlot(other, slot);
       if (val1 !== val2) return false;
     }
-    return ES.CalendarEquals(this, other);
+    return ES.CalendarEquals(GetSlot(this, CALENDAR), GetSlot(other, CALENDAR));
   }
   toString(options = undefined) {
     if (!ES.IsTemporalDateTime(this)) throw new TypeError('invalid receiver');

lib/plainmonthday.ts

@@ -73,7 +73,7 @@ export class PlainMonthDay implements Temporal.PlainMonthDay {
       const val2 = GetSlot(other, slot);
       if (val1 !== val2) return false;
     }
-    return ES.CalendarEquals(this, other);
+    return ES.CalendarEquals(GetSlot(this, CALENDAR), GetSlot(other, CALENDAR));
   }
   toString(options = undefined) {
     if (!ES.IsTemporalMonthDay(this)) throw new TypeError('invalid receiver');

lib/plainyearmonth.ts

@@ -278,7 +278,7 @@ export class PlainYearMonth implements Temporal.PlainYearMonth {
       const val2 = GetSlot(other, slot);
       if (val1 !== val2) return false;
     }
-    return ES.CalendarEquals(this, other);
+    return ES.CalendarEquals(GetSlot(this, CALENDAR), GetSlot(other, CALENDAR));
   }
   toString(options = undefined) {
     if (!ES.IsTemporalYearMonth(this)) throw new TypeError('invalid receiver');