recur_expansion: EXDATE can be DATE and DTSTART can be DATE-TIME

When EXDATE is in DATE format and DTSTART is DATE-TIME, then
to determine whether a ocurrence shall be excluded, the
occurence shall be converted to DATE and then compared to EXDATE.

This applies also for the very first EXDATE, when it coincides with
DTSTART.

lib/ical/recur_expansion.js

@@ -213,6 +213,21 @@ ICAL.RecurExpansion = (function() {
       }
     },
 
+    /**
+     * Compare two ICAL.Time objects.  When the second parameter is a timeless date
+     * and the first parameter is date-with-time, strip the time and compare only
+     * the days.
+     *
+     * @private
+     * @param {ICAL.Time} a   The one object to compare
+     * @param {ICAL.Time} b   The other object to compare
+     */
+    _compare_special: function(a, b) {
+        if (!a.isDate && b.isDate)
+	    return new ICAL.Time({year:a.year, month:a.month, day:a.day}).compare(b);
+        else return a.compare(b);
+    },
+
     /**
      * Retrieve the next occurrence in the series.
      * @return {ICAL.Time}
@@ -264,9 +279,10 @@ ICAL.RecurExpansion = (function() {
 
         // check the negative rules
         if (this.exDate) {
-          compare = this.exDate.compare(this.last);
+          //EXDATE can be in DATE format, but DTSTART is in DATE-TIME format
+          compare = this._compare_special(this.last, this.exDate);
 
-          if (compare < 0) {
+          if (compare > 0) {
             this._nextExDay();
           }
 
@@ -418,10 +434,12 @@ ICAL.RecurExpansion = (function() {
       if (component.hasProperty('exdate')) {
         this.exDates = this._extractDates(component, 'exdate');
         // if we have a .last day we increment the index to beyond it.
+        // When DTSTART is in DATE-TIME format, EXDATE is in DATE format and EXDATE is
+        // the date of DTSTART, _compare_special finds this out and compareTime fails.
         this.exDateInc = ICAL.helpers.binsearchInsert(
           this.exDates,
           this.last,
-          compareTime
+          this._compare_special
         );
 
         this.exDate = this.exDates[this.exDateInc];