Adding workaround to jump in wallpaper offsets.

- Just skip the animation if we are animating to the same wallpaper 
  offset (which is the case when we are adding from all apps)

Bug: 28587903
Change-Id: Ib7b1828c1b099a665d68c22cb33ee62693f33f35

src/com/android/launcher3/util/WallpaperOffsetInterpolator.java

@@ -208,8 +208,9 @@ public class WallpaperOffsetInterpolator implements Choreographer.FrameCallback
         scheduleUpdate();
         mFinalOffset = Math.max(0f, Math.min(x, 1f));
         if (getNumScreensExcludingEmptyAndCustom() != mNumScreens) {
-            if (mNumScreens > 0) {
-                // Don't animate if we're going from 0 screens
+            if (mNumScreens > 0 && Float.compare(mCurrentOffset, mFinalOffset) != 0) {
+                // Don't animate if we're going from 0 screens, or if the final offset is the same
+                // as the current offset
                 animateToFinal();
             }
             mNumScreens = getNumScreensExcludingEmptyAndCustom();