bpo-33975: Avoid small type when running IDLE's htests. (GH-7944)

Import pyshell first in htest to call SetProcessDpiAwareness on Windows
before tkinter.Tk() is called for the htest. Apparently, 'root.destroy()'
undoes a previous 'root = Tk()'. Since IDLE unittests always destroy roots,
a unittest before an htest does not require anything more to work right.
Since part of the purpose of human-viewed tests is to determine that
widgets look right, it is important that they look the same for testing
as when running IDLE.

Lib/idlelib/idle_test/htest.py

@@ -65,6 +65,7 @@ autocomplete_w.AutoCompleteWindow
 outwin.OutputWindow (indirectly being tested with grep test)
 '''
 
+import idlelib.pyshell  # Set Windows DPI awareness before Tk().
 from importlib import import_module
 import tkinter as tk
 from tkinter.ttk import Scrollbar

Misc/NEWS.d/next/IDLE/2018-06-26-22-53-14.bpo-33975.Ow7alv.rst

+Avoid small type when running htests. Since part of the purpose of human-
+viewed tests is to determine that widgets look right, it is important that
+they look the same for testing as when running IDLE.