The result of wfEscapeWikiText() did not consider inclusion of a string
within table context, and so `!!` and `!` at start of line were not
previously escaped.
Additionally, if you are inserting the result of wfEscapeWikiText()
into a wikitext string, the result can inadventently form new tokens
at the left and right edges. For example:
{|
|<escaped string>
When the escaped string starts with a `-` or `+` it forms the `|-` or `|+`
token and changes the parse.
On the right side:
<escaped string>_FORCETOC__
is not a magic word unless the escaped string ends with a `_`.
Token-gluing can also occur with the double newline token denoting
a paragraph separator.
This patch adds additional cases to wfEscapeWikiText to armor
its output against all contexts in which the output may be
inserted.
Depends-On: I56147520620d56a4b98c2f22d1f469b49aed761f
Change-Id: I34f2fa8c329e6f6771453b2f94dc4afbec31dac8
3fc635dcb2