import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1147491, part 1 - Fix playbackRate crash due to integer rounding causing divide-by-zero. r=dholbert (7726fc9ce)
- Bug 1147491, part 2 - Disable use of BaseTimeDuration::operator/ with floating point values. r=ehsan (073909011)
- Bug 1147491 - Partially backout part 2 while figuring out B2G orange. r=orange CLOSED TREE (b37b02f50)
- Bug 1147491, part 2 - Disable use of BaseTimeDuration::operator/ with floating point values. r=ehsan (ca7cffb4d)

dom/animation/AnimationPlayer.cpp

@@ -107,7 +107,7 @@ AnimationPlayer::SilentlySetCurrentTime(const TimeDuration& aSeekTime)
     }
   } else {
     mStartTime.SetValue(mTimeline->GetCurrentTime().Value() -
-                          (aSeekTime / mPlaybackRate));
+                          (aSeekTime.MultDouble(1 / mPlaybackRate)));
   }
 
   mPreviousCurrentTime.SetNull();
@@ -604,7 +604,8 @@ AnimationPlayer::ResumeAt(const TimeDuration& aReadyTime)
   // we should use. In all other cases, we resolve it from the ready time.
   if (mStartTime.IsNull()) {
     if (mPlaybackRate != 0) {
-      mStartTime.SetValue(aReadyTime - (mHoldTime.Value() / mPlaybackRate));
+      mStartTime.SetValue(aReadyTime -
+                          (mHoldTime.Value().MultDouble(1 / mPlaybackRate)));
       mHoldTime.SetNull();
     } else {
       mStartTime.SetValue(aReadyTime);
@@ -679,7 +680,7 @@ AnimationPlayer::UpdateFinishedState(bool aSeekFlag)
                !currentTime.IsNull()) {
       if (aSeekFlag && !mHoldTime.IsNull()) {
         mStartTime.SetValue(mTimeline->GetCurrentTime().Value() -
-                              (mHoldTime.Value() / mPlaybackRate));
+                              (mHoldTime.Value().MultDouble(1 / mPlaybackRate)));
       }
       mHoldTime.SetNull();
     }

mfbt/RollingMean.h

@@ -86,7 +86,7 @@ public:
   T mean()
   {
     MOZ_ASSERT(!empty());
-    return T(mTotal / mValues.length());
+    return T(mTotal / int64_t(mValues.length()));
   }
 
   bool empty()

widget/gonk/GeckoTouchDispatcher.cpp

@@ -271,7 +271,7 @@ GoannaTouchDispatcher::ResampleTouchMoves(MultiTouchInput& aOutTouch, TimeStamp
   TimeDuration touchDiff = currentTouch.mTimeStamp - baseTouch.mTimeStamp;
 
   if (currentTouch.mTimeStamp < sampleTime) {
-    TimeDuration maxResampleTime = std::min(touchDiff / 2, mMaxPredict);
+    TimeDuration maxResampleTime = std::min(touchDiff / int64_t(2), mMaxPredict);
     TimeStamp maxTimestamp = currentTouch.mTimeStamp + maxResampleTime;
     if (sampleTime > maxTimestamp) {
       sampleTime = maxTimestamp;

xpcom/ds/TimeStamp.h

@@ -181,6 +181,11 @@ private:
   // If required, use MultDouble explicitly and with care.
   BaseTimeDuration operator*(const double aMultiplier) const = delete;
 
+  // Block double divisor (for the same reason, and because dividing by
+  // fractional values would otherwise invoke the int64_t variant, and rounding
+  // the passed argument can then cause divide-by-zero) - Bug 1147491.
+  BaseTimeDuration operator/(const double aDivisor) const = delete;
+
 public:
   BaseTimeDuration MultDouble(double aMultiplier) const
   {