Fix span of xml literal with CR-NL

Forward port scala/scala@f428cc6

Author: som-snytt

compiler/src/dotty/tools/dotc/parsing/xml/MarkupParsers.scala

@@ -74,7 +74,10 @@ object MarkupParsers {
 
     import parser.{ symbXMLBuilder => handle }
 
-    def curOffset : Int = input.charOffset - 1
+    def curOffset : Int =
+      val res = input.charOffset - 1
+      if res > 0 && input.buf(res) == '\n' && input.buf(res-1) == '\r' then res - 1 else res
+
     var tmppos : Span = NoSpan
     def ch: Char = input.ch
     /** this method assign the next character to ch and advances in input */
@@ -342,14 +345,14 @@ object MarkupParsers {
     }
 
     /** Use a lookahead parser to run speculative body, and return the first char afterward. */
-    private def charComingAfter(body: => Unit): Char = {
+    private def charComingAfter(body: => Unit): Char =
+      val saved = input
       try {
         input = input.lookaheadReader()
         body
         ch
       }
-      finally input = parser.in
-    }
+      finally input = saved
 
     /** xLiteral = element { element }
      *  @return Scala representation of this xml literal
@@ -361,7 +364,6 @@ object MarkupParsers {
 
         val ts = new ArrayBuffer[Tree]
         val start = curOffset
-        tmppos = Span(curOffset)    // Iuli: added this line, as it seems content_LT uses tmppos when creating trees
         content_LT(ts)
 
         // parse more XML?