Fix mutation of method name in mocker.
Fix mutation of method name in mocker.

This bug reveals itself in PHP7.
Fixes #1240.

whowgames/lithium,whowgames/lithium,UnionOfRAD/lithium,m4rcsch/lithium-core-library,datachand/lithium,UnionOfRAD/lithium,datachand/lithium,m4rcsch/lithium-core-library