The flow just before it become unreachable

Property definitions

nitc :: flow $ AEscapeExpr :: before_flow_context
	# The flow just before it become unreachable
	fun before_flow_context: nullable FlowContext
	do
		var after = self.after_flow_context
		if after == null then return null
		return after.previous.first
	end
src/semantize/flow.nit:323,2--329,4