Revert "Revert "Clear the bitmap associated with canvases.""

This reverts commit 4e012846cd09caa85b018c36810e9a64adb87640.
diff --git a/src/com/android/launcher2/IconCache.java b/src/com/android/launcher2/IconCache.java
index 3dc7808..04f97f3 100644
--- a/src/com/android/launcher2/IconCache.java
+++ b/src/com/android/launcher2/IconCache.java
@@ -104,6 +104,7 @@
         Canvas c = new Canvas(b);
         d.setBounds(0, 0, b.getWidth(), b.getHeight());
         d.draw(c);
+        c.setBitmap(null);
         return b;
     }