Correct the controls test refactoring to eliminate the circular dependency
 that was missed. The shim classes cannot depend on the test classes.

com/sun/javafx/scene/control/ContextMenuContentShim.java:import test.com.sun.javafx.scene.control.infrastructure.KeyEventFirer;
com/sun/javafx/scene/control/ContextMenuContentShim.java:import test.com.sun.javafx.scene.control.infrastructure.MouseEventFirer;
javafx/scene/control/skin/TableColumnHeaderShim.java:import test.com.sun.javafx.scene.control.infrastructure.VirtualFlowTestUtils;