fix today's pseudo-blocker by initializing a variable which determined if the "Now" value was valid or not

r=pchen, sr=blizzard

xpfe/components/history/src/nsGlobalHistory.cpp

@@ -415,6 +415,7 @@ nsGlobalHistory::nsGlobalHistory()
     mStore(nsnull),
     mTable(nsnull),
     mExpireDays(9), // make default be nine days
+    mNowValid(PR_FALSE),
     mDirty(PR_FALSE)
 {
   NS_INIT_REFCNT();