Dates with missing UTC offset should be interpreted (in nashorn-compat mode) as UTC time when they are "strict" only.

(cherry picked from commit 35d5ca1)

Author: iamstolis

graal-js/src/com.oracle.truffle.js.parser/src/com/oracle/truffle/js/parser/date/DateParser.java

@@ -746,7 +746,8 @@ private boolean patchResult(final boolean strict) {
     }
 
     private boolean isUTCDefaultTimezone(boolean dateOnly, boolean strict) {
-        return (strict || realm.getContext().getLanguageOptions().useUTCForLegacyDates()) && dateOnly;
+        return realm.getContext().isOptionNashornCompatibilityMode() ? strict :
+                (dateOnly && (strict || realm.getContext().getLanguageOptions().useUTCForLegacyDates()));
     }
 
     private static void addName(final String str, final int type, final int value) {