There is no reason to port yii2-Di-Container to php 5.3 as the minimum requirement for yii2 is php 5.4.
To use yii2 you must update to php 5.4 at least (better to 5.5).
Consider also that php 5.3 has stopped the maintenance 14 Aug 2014, so any security and bug that arise is not fixed anymore.
Something that should incentive you to the upgrade is also that 5.4 vs 5.3 use less memory (much less by my own experience) and has increased performance.