MAINT: Pass data_frequency to get_history_window

This allows us to remove the check for whether the provided dt had a
time of midnight, which was a flimsy way to infer if the data frequency
was 'daily'. Besides the explicit check being preferable, this method
was broken on the futures calendar, since midnight is a valid market
minute.

zipline/algorithm.py

@@ -2160,6 +2160,7 @@ class TradingAlgorithm(object):
                 bar_count,
                 frequency,
                 field,
+                self.data_frequency,
                 ffill,
             )
         else:
@@ -2176,6 +2177,7 @@ class TradingAlgorithm(object):
                 bar_count,
                 frequency,
                 field,
+                self.data_frequency,
                 ffill,
             )