Remove blank lines from error message (#8550)

packages/flutter/lib/src/rendering/viewport.dart

@@ -514,7 +514,6 @@ class RenderViewport extends RenderViewportBase<SliverPhysicalContainerParentDat
                 'In this case, a vertical viewport was given an unlimited amount of '
                 'vertical space in which to expand. This situation typically happens '
                 'when a scrollable widget is nested inside another scrollable widget.\n'
-                '\n'
                 'If this widget is always nested in a scrollable widget there '
                 'is no need to use a viewport because there will always be enough '
                 'vertical space for the children. In this case, consider using a '
@@ -541,7 +540,6 @@ class RenderViewport extends RenderViewportBase<SliverPhysicalContainerParentDat
                 'In this case, a horizontal viewport was given an unlimited amount of '
                 'horizontal space in which to expand. This situation typically happens '
                 'when a scrollable widget is nested inside another scrollable widget.\n'
-                '\n'
                 'If this widget is always nested in a scrollable widget there '
                 'is no need to use a viewport because there will always be enough '
                 'horizontal space for the children. In this case, consider using a '