Fix bug where stack view was getting clipped

We were also updating CellLayouts' drawing cache even when not needed, this is now fixed (and was actually the cause of the bug)
diff --git a/src/com/android/launcher2/CellLayout.java b/src/com/android/launcher2/CellLayout.java
index 121aa22..fd1f048 100644
--- a/src/com/android/launcher2/CellLayout.java
+++ b/src/com/android/launcher2/CellLayout.java
@@ -437,8 +437,9 @@
             }
         }
 
+        boolean useBitmapCache = mIsCacheEnabled && getScaleX() < mMaxScaleForUsingBitmapCache;
         if (mForceCacheUpdate ||
-                (mIsCacheEnabled && !mDisableCacheUpdates)) {
+                (useBitmapCache && !mDisableCacheUpdates)) {
             // Sometimes we force a cache update-- this is used to make sure the cache will look as
             // up-to-date as possible right when we disable cache updates
             if (mIsCacheDirty) {
@@ -447,7 +448,7 @@
             mForceCacheUpdate = false;
         }
 
-        if (mIsCacheEnabled && getScaleX() < mMaxScaleForUsingBitmapCache) {
+        if (useBitmapCache) {
             mCachePaint.setAlpha((int)(255*getAlpha()));
             canvas.drawBitmap(mCache, mCacheRect, mBackgroundRect, mCachePaint);
         } else {