bpo-35087: Update idlelib help files for the current doc build. (GH-10162)

There is only one trivial change to idle.rst. Nearly all the changes to help.html are the elimination of chapter and section numbers on headers due to changes in the build system. help.py no longer requires header numbering.
(cherry picked from commit db40cb50)
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Lib/idlelib/help.py

@@ -126,7 +126,10 @@ class HelpParser(HTMLParser):
         if tag in ['h1', 'h2', 'h3']:
             self.indent(0)  # clear tag, reset indent
             if self.show:
-                self.toc.append((self.header, self.text.index('insert')))
+                indent = ('        ' if tag == 'h3' else
+                          '    ' if tag == 'h2' else
+                          '')
+                self.toc.append((indent+self.header, self.text.index('insert')))
         elif tag in ['span', 'em']:
             self.chartags = ''
         elif tag == 'a':
@@ -142,11 +145,15 @@ class HelpParser(HTMLParser):
         if self.show and not self.hdrlink:
             d = data if self.pre else data.replace('\n', ' ')
             if self.tags == 'h1':
+                try:
                     self.hprefix = d[0:d.index(' ')]
-            if self.tags in ['h1', 'h2', 'h3'] and self.hprefix != '':
-                if d[0:len(self.hprefix)] == self.hprefix:
-                    d = d[len(self.hprefix):].strip()
-                self.header += d
+                except ValueError:
+                    self.hprefix = ''
+            if self.tags in ['h1', 'h2', 'h3']:
+                if (self.hprefix != '' and
+                    d[0:len(self.hprefix)] == self.hprefix):
+                    d = d[len(self.hprefix):]
+                self.header += d.strip()
             self.text.insert('end', d, (self.tags, self.chartags))
 
 

Misc/NEWS.d/next/IDLE/2018-10-28-00-08-42.bpo-35087.G7gx2-.rst

+Update idlelib help files for the current doc build. The main change is the
+elimination of chapter-section numbers.