84988 Adds mainAxisMargin property to RawScrollbar (severe: new feature, framework, f: scrolling, cla: yes, waiting for tree to go green)

85152 DismissDirection.none will not prevent scrolling (framework, f: scrolling, cla: yes, a: quality, waiting for tree to go green)

85221 [new feature]introduce ScrollMetricsNotification (severe: new feature, framework, f: scrolling, cla: yes, waiting for tree to go green)

85338 Expose minThumbLength, crossAxisMargin, and minOverscrollLength on RawScrollbar (severe: new feature, framework, f: scrolling, cla: yes, waiting for tree to go green)

85499 Re-land”[new feature]introduce ScrollMetricsNotification” (severe: new feature, framework, f: scrolling, cla: yes, customer: crowd, waiting for tree to go green)