Bug 456165 part 2. Trace Date.now. r=gal

js/src/jsbuiltins.cpp

@@ -51,6 +51,7 @@
 #include "jslibmath.h"
 #include "jsmath.h"
 #include "jsnum.h"
+#include "prmjtime.h"
 #include "jsscope.h"
 #include "jsstr.h"
 #include "jstracer.h"
@@ -862,6 +863,12 @@ js_Arguments(JSContext* cx)
     return NULL;
 }
 
+jsdouble FASTCALL
+js_Date_now(JSContext*)
+{
+    return PRMJ_Now() / PRMJ_USEC_PER_MSEC;
+}
+
 /* soft float */
 
 jsdouble FASTCALL