Fixes #2761. Small TextView is broken scrolling using scrollbar.

[BDisp]

Fixes #2761 - The principal culprit is the SetRelativeLayout being called with the wrong Frame value. For e.g. a TextView inside a FrameView but using the Window's ContentView.Frame instead of FrameView.Frame.

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[BDisp]

@tig I'll add more unit tests to guarantee that this doesn't happens anymore.

[BDisp]

I think it's all done @tig.
@chr1st0scli I added the follow on the unit tests to the TextViewScrollBarView because BottonOffset isn't be set as it was sets before subscribing the event and thus ensure get his state on driver initialization.

				Initialized += TextViewScrollBarView_Initialized;
				OtherScrollBarView.Initialized += OtherScrollBarView_Initialized;

[tig]

@BDisp can you bring this fix forward into v2_develop too? Thanks.