Fix Transformer ToolsBar toggling

Summary:
The different transformation tool buttons stopped toggling when pressed,
preventing you from unsummoning a tool after it was summoned, except by
summoning a different tool. This change fixes the ability to unsummon a
tool by clicking that tool's button again (which should be in a
depressed state before this second click).

Test Plan:
visit test.html
add a rotation tool
click the rotation button again
verify that there are no transformation tools on the graph anymore