Fix 'illegal access' in Date constructor edge case

src/date.h

Index: src/date.h
diff --git a/src/date.h b/src/date.h
index 813e5b83c0bb763d2cd338cccf4d7c1464e3ad63..035ead6d48453aa0eecf35f90f5541e0144f86b8 100644
--- a/src/date.h
+++ b/src/date.h
@@ -18,6 +18,7 @@ class DateCache {
   static const int kMsPerMin = 60 * 1000;
   static const int kSecPerDay = 24 * 60 * 60;
   static const int64_t kMsPerDay = kSecPerDay * 1000;
+  static const int64_t kMsPerMonth = kMsPerDay * 30;
 
   // The largest time that can be passed to OS date-time library functions.
   static const int kMaxEpochTimeInSec = kMaxInt;
@@ -30,8 +31,7 @@ class DateCache {
 
   // Conservative upper bound on time that can be stored in JSDate
   // before UTC conversion.
-  static const int64_t kMaxTimeBeforeUTCInMs =
-      kMaxTimeInMs + 10 * kMsPerDay;
+  static const int64_t kMaxTimeBeforeUTCInMs = kMaxTimeInMs + kMsPerMonth;
 
   // Sentinel that denotes an invalid local offset.
   static const int kInvalidLocalOffsetInMs = kMaxInt;