Revert "Bug 1029766 - Intermittent TEST-UNEXPECTED-FAIL | collection_test.js | Vertical - Collection drag icon (/w entry point) into collection r=crdlc"

This reverts commit 6cb2e93790340d18d771a4c532ecfb968fa38c51.
Bug 1029766 - Intermittent TEST-UNEXPECTED-FAIL | collection_test.js | Vertical - Collection drag icon (/w entry point) into collection r=crdlc