Parsing: Added stateInHtmlBlock to ParserState.

This is used to keep track of the ending tag we're waiting
for when we're parsing inside HTML block tags.

src/Text/Pandoc/Parsing.hs

@@ -863,6 +863,7 @@ data ParserState = ParserState
       -- roles), 3) Source language annotation for code (could be used to
       -- annotate role classes too).
       stateCaption         :: Maybe Inlines, -- ^ Caption in current environment
+      stateInHtmlBlock     :: Maybe String,  -- ^ Tag type of HTML block being parsed
       stateWarnings        :: [String]       -- ^ Warnings generated by the parser
     }
 
@@ -941,6 +942,7 @@ defaultParserState =
                   stateRstDefaultRole  = "title-reference",
                   stateRstCustomRoles  = M.empty,
                   stateCaption         = Nothing,
+                  stateInHtmlBlock     = Nothing,
                   stateWarnings        = []}
 
 -- | Succeed only if the extension is enabled.