Polyfill: Correctly calculate negative leap years in Hebrew calendar

We need to do the non-negative modulo here, otherwise all negative years
are leap years.

Author: ptomato

polyfill/lib/calendar.mjs

@@ -1243,7 +1243,9 @@ const helperHebrew = makeNonISOHelper([{ code: 'am', isoEpoch: { year: -3760, mo
     // Given that these can be calculated by counting the number of days in
     // those months, I assume that these DO NOT need to be exposed as
     // Hebrew-only prototype fields or methods.
-    return (7 * year + 1) % 19 < 7;
+    let cycleYear = (7 * year + 1) % 19;
+    if (cycleYear < 0) cycleYear += 19;
+    return cycleYear < 7;
   },
   monthsInYear(calendarDate) {
     return this.inLeapYear(calendarDate) ? 13 : 12;