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

This reverts commit 4e012846cd09caa85b018c36810e9a64adb87640.
diff --git a/src/com/android/launcher2/Utilities.java b/src/com/android/launcher2/Utilities.java
index 7758333..c63c822 100644
--- a/src/com/android/launcher2/Utilities.java
+++ b/src/com/android/launcher2/Utilities.java
@@ -145,6 +145,7 @@
             icon.setBounds(left, top, left+width, top+height);
             icon.draw(canvas);
             icon.setBounds(sOldBounds);
+            canvas.setBitmap(null);
 
             return bitmap;
         }
@@ -211,6 +212,8 @@
             
             canvas.drawBitmap(bitmap, 0.0f, 0.0f, sDisabledPaint);
 
+            canvas.setBitmap(null);
+
             return disabled;
         }
     }
@@ -327,6 +330,7 @@
                 c.drawText(lineText, x, y, mTextPaint);
             }
 
+            c.setBitmap(null);
             return b;
         }