Revert "Clear mFreeBoxIndices to remove the indices that were removed from shrinking"

This reverts commit 31c453f.

This needs to be looked at again. This was not the right fix.

Author: kitskub

src/main/java/org/spout/physics/collision/broadphase/SweepAndPruneAlgorithm.java

@@ -393,7 +393,6 @@ private void shrinkArrays() {
                 newMapBodyToBoxIndex.put(body, boxIndex);
             }
         }
-        mFreeBoxIndices.clear();
         if (newMapBodyToBoxIndex.size() != mMapBodyToBoxIndex.size()) {
             throw new IllegalStateException("The size of the new map from body to box index must be the same as the old one");
         }