Add parens to DateYMDFromTimeSlow to clearify.

src/runtime.cc

Index: src/runtime.cc
===================================================================
--- src/runtime.cc	(revision 4186)
+++ src/runtime.cc	(working copy)
@@ -5731,11 +5731,11 @@
   bool is_leap = (!yd1 || yd2) && !yd3;
 
   ASSERT(date >= -1);
-  ASSERT(is_leap || date >= 0);
-  ASSERT(date < 365 || is_leap && date < 366);
-  ASSERT(is_leap == (year % 4 == 0 && (year % 100 || (year % 400 == 0))));
-  ASSERT(is_leap || MakeDay(year, 0, 1) + date == save_date);
-  ASSERT(!is_leap || MakeDay(year, 0, 1) + date + 1 == save_date);
+  ASSERT(is_leap || (date >= 0));
+  ASSERT((date < 365) || (is_leap && (date < 366)));
+  ASSERT(is_leap == ((year % 4 == 0) && (year % 100 || (year % 400 == 0))));
+  ASSERT(is_leap || ((MakeDay(year, 0, 1) + date) == save_date));
+  ASSERT(!is_leap || ((MakeDay(year, 0, 1) + date + 1) == save_date));
 
   if (is_leap) {
     day = kDayInYear[2*365 + 1 + date];