Revert "Do not expose removeAllChildren on WrapperNode"

This reverts commit b97449ef03d2389d6c00648a37936c9413d97e19.

It broke the test. textContent is not updating the internal pointers correctly
Merge pull request #22 from arv/revert-remove-all-child-nodes

Revert "Do not expose removeAllChildren on WrapperNode"