Fix more warnings in wtf

Source/wtf/DateMath.cpp

 /*
  * Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  * Copyright (C) 2010 &yet, LLC. (nate@andyet.net)
  *
  * The Original Code is Mozilla Communicator client code, released
  * March 31, 1998.
  *
@@ skipping 82 matching lines @@
 #if HAVE(SYS_TIME_H)
 #include <sys/time.h>
 #endif
 
 using namespace WTF;
 
 namespace WTF {
 
 /* Constants */
 
-static const double minutesPerDay = 24.0 * 60.0;
 static const double secondsPerDay = 24.0 * 60.0 * 60.0;
-static const double secondsPerYear = 24.0 * 60.0 * 60.0 * 365.0;
-
-static const double usecPerSec = 1000000.0;
 
 static const double maxUnixTime = 2145859200.0; // 12/31/2037
 // ECMAScript asks not to support for a date of which total
 // millisecond value is larger than the following value.
 // See 15.9.1.14 of ECMA-262 5th edition.
 static const double maxECMAScriptTime = 8.64E15;
 
 // Day of year for the first day of each month, where index 0 is January, and day 0 is January 1.
 // First for non-leap years, then for leap years.
 static const int firstDayOfMonth[2][12] = {
@@ skipping 960 matching lines @@
 
     stringBuilder.append(utcOffset > 0 ? '+' : '-');
     int absoluteUTCOffset = abs(utcOffset);
     stringBuilder.append(twoDigitStringFromNumber(absoluteUTCOffset / 60));
     stringBuilder.append(twoDigitStringFromNumber(absoluteUTCOffset % 60));
 
     return stringBuilder.toString();
 }
 
 } // namespace WTF