Per bug 1141415 comment 44, we need a way to make PR_Now() and Date.now() consistent on win32 platform(winXP and win7).

You can't make them consistent. They use different time sources that can have skew and are not terribly accurate anyway. Not to mention that they can both run backwards, which I expect is a problem for the use described in bug 1141415. For consistent times within a process runtime you should use TimeStamp in C++ and performance.now() in JS, with the appropriate offsetting from one to the other based on what the zero