Merge commit '257d49'

Merge commit '257d49'

Conflicts:
	tests/testbench/com/vaadin/tests/application/PaintableIdsShouldBeUnique.java
	tests/testbench/com/vaadin/tests/components/TestBase.java
	tests/testbench/com/vaadin/tests/components/table/ScrollCausesRequestLoop.java
	tests/testbench/com/vaadin/tests/components/table/ScrollDetachSynchronization.java
	tests/testbench/com/vaadin/tests/components/table/TableClickValueChangeInteraction.java
	tests/testbench/com/vaadin/tests/components/window/ReplacingComponentsInHandleParameters.java
	tests/testbench/com/vaadin/tests/containers/TableWithFileSystemContainer.java
	tests/testbench/com/vaadin/tests/layouts/GridLayoutCaptions.java
	tests/testbench/com/vaadin/tests/layouts/GridLayoutExpandRatioModification.java
	tests/testbench/com/vaadin/tests/layouts/VerticalLayoutExpandRatioModification.java
	tests/testbench/com/vaadin/tests/tickets/Ticket6002.java

Changed tests creating their own main windows (without a good reason) and extending AbstractTestBase to call getMainWindow() and extend TestBase instead