Start to update AAA. This gets the tests passing.

However, all the comments should be updated.

html5lib/constants.py

@@ -180,6 +180,9 @@
  "adoption-agency-1.3":
  _("End tag (%(name)s) violates step 1, "
  "paragraph 3 of the adoption agency algorithm."),
+ "adoption-agency-4.4":
+ _("End tag (%(name)s) violates step 4, "
+ "paragraph 4 of the adoption agency algorithm."),
  "unexpected-end-tag-treated-as":
  _("Unexpected end tag (%(originalName)s). Treated as %(newName)s."),
  "no-end-tag":

html5lib/html5parser.py

@@ -1404,28 +1404,60 @@ def endTagFormatting(self, token):
  # XXX Better parseError messages appreciated.
  name = token["name"]
 
+ # Step 1
  outerLoopCounter = 0
+
+ # Step 2
  while outerLoopCounter < 8:
+
+ # Step 3
  outerLoopCounter += 1
 
- # Step 1 paragraph 1
+ # Step 4:
+
+ # Let the formatting element be the last element in
+ # the list of active formatting elements that:
+ # - is between the end of the list and the last scope
+ # marker in the list, if any, or the start of the list
+ # otherwise, and
+ # - has the same tag name as the token.
  formattingElement = self.tree.elementInActiveFormattingElements(
  token["name"])
  if (not formattingElement or 
  (formattingElement in self.tree.openElements and
  not self.tree.elementInScope(formattingElement.name))):
- self.parser.parseError("adoption-agency-1.1", {"name": token["name"]})
+ # If there is no such node, then abort these steps
+ # and instead act as described in the "any other
+ # end tag" entry below.
+ self.endTagOther(token)
  return
 
- # Step 1 paragraph 2
+ # Otherwise, if there is such a node, but that node is
+ # not in the stack of open elements, then this is a
+ # parse error; remove the element from the list, and
+ # abort these steps.
  elif formattingElement not in self.tree.openElements:
  self.parser.parseError("adoption-agency-1.2", {"name": token["name"]})
  self.tree.activeFormattingElements.remove(formattingElement)
  return
+
+
+ # Otherwise, if there is such a node, and that node is
+ # also in the stack of open elements, but the element
+ # is not in scope, then this is a parse error; ignore
+ # the token, and abort these steps.
+ elif not self.tree.elementInScope(formattingElement.name):
+ self.parser.parseError("adoption-agency-4.4", {"name": token["name"]})
+ return
 
- # Step 1 paragraph 3
- if formattingElement != self.tree.openElements[-1]:
- self.parser.parseError("adoption-agency-1.3", {"name": token["name"]})
+ # Otherwise, there is a formatting element and that
+ # element is in the stack and is in scope. If the
+ # element is not the current node, this is a parse
+ # error. In any case, proceed with the algorithm as
+ # written in the following steps.
+ else:
+ if formattingElement != self.tree.openElements[-1]:
+ self.parser.parseError("adoption-agency-1.3", {"name": token["name"]})
 
  # Step 2
  # Start of the adoption agency algorithm proper