Avoid useless initialization in ScrollAnimatorNone::PerAxisData::animateScroll()

Source/platform/scroll/ScrollAnimatorNone.cpp

 /*
  * Copyright (c) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 316 matching lines @@
 // FIXME: Add in jank detection trace events into this function.
 bool ScrollAnimatorNone::PerAxisData::animateScroll(double currentTime)
 {
     double lastScrollInterval = currentTime - m_lastAnimationTime;
     if (lastScrollInterval < kMinimumTimerInterval)
         return true;
 
     m_lastAnimationTime = currentTime;
 
     double deltaTime = currentTime - m_startTime;
-    double newPosition = *m_currentPosition;
 
     if (deltaTime > m_animationTime) {
         *m_currentPosition = m_desiredPosition;
         reset();
         return false;
     }
-    if (deltaTime < m_attackTime)
+    double newPosition;

[abarth-chromium, 2014/04/20 14:10:05]

Can we initialize it to zero?  We generally like to initialize scalars.

[Inactive, 2014/04/20 15:00:56]

Counter proposal: I moved the initialization to a new inline function and
newPosition is now initialized with the the result of this new function. This
way we avoid the useless assignment, *and* the scalar is initialized. PTAL.

+    if (deltaTime < m_attackTime) {
         newPosition = attackCurve(m_attackCurve, deltaTime, m_attackTime, m_startPosition, m_attackPosition);
-    else if (deltaTime < (m_animationTime - m_releaseTime))
+    } else if (deltaTime < (m_animationTime - m_releaseTime)) {
         newPosition = m_attackPosition + (deltaTime - m_attackTime) * m_desiredVelocity;
-    else {
+    } else {
         // release is based on targeting the exact final position.
         double releaseDeltaT = deltaTime - (m_animationTime - m_releaseTime);
         newPosition = releaseCurve(m_releaseCurve, releaseDeltaT, m_releaseTime, m_releasePosition, m_desiredPosition);
     }
 
     // Normalize velocity to a per second amount. Could be used to check for jank.
     if (lastScrollInterval > 0)
         m_currentVelocity = (newPosition - *m_currentPosition) / lastScrollInterval;
     *m_currentPosition = newPosition;
 
@@ skipping 158 matching lines @@
     return m_animationActive;
 }
 
 void ScrollAnimatorNone::stopAnimationTimerIfNeeded()
 {
     if (animationTimerActive())
         m_animationActive = false;
 }
 
 } // namespace WebCore