Bug 1439657 Remove Time Precision Reduction from Console Timestamps r=baku

We currently reduce the precision of timestamps emitted by console.time
in the main context, but not in a Worker. Because web page content cannot
read the content of messages emitted to the console (right?), we don't
actually need to reduce the precision of this data.

MozReview-Commit-ID: EfpIEICy0tX

--HG--
extra : rebase_source : 9516943b11dd7d4ccbcf38a80a981a6fb4662c40

dom/console/Console.cpp

@@ -2544,14 +2544,7 @@ Console::MonotonicTimer(JSContext* aCx, MethodName aMethodName,
   }
 
   if (NS_IsMainThread()) {
-    double duration = (TimeStamp::Now() - mCreationTimeStamp).ToMilliseconds();
-
-    // Round down to the nearest 5us, because if the timer is too accurate
-    // people can do nasty timing attacks with it.  See similar code in the
-    // worker Performance implementation.
-    const double maxResolutionMs = 0.005;
-    *aTimeStamp = nsRFPService::ReduceTimePrecisionAsMSecs(
-      floor(duration / maxResolutionMs) * maxResolutionMs);
+    *aTimeStamp = (TimeStamp::Now() - mCreationTimeStamp).ToMilliseconds();
     return true;
   }