Update TastyFormat for flexible types

Author: noti0na1

tasty/src/dotty/tools/tasty/TastyFormat.scala

@@ -176,6 +176,7 @@ Standard-Section: "ASTs" TopLevelStat*
                   ORtype         Length left_Type right_Type                       -- lefgt | right
                   MATCHtype      Length bound_Type sel_Type case_Type*             -- sel match {cases} with optional upper `bound`
                   MATCHCASEtype  Length pat_type rhs_Type                          -- match cases are MATCHCASEtypes or TYPELAMBDAtypes over MATCHCASEtypes
+                  FLEXIBLEtype   Length underlying_Type                            -- (underlying)?
                   BIND           Length boundName_NameRef bounds_Type Modifier*    -- boundName @ bounds,  for type-variables defined in a type pattern
                   BYNAMEtype            underlying_Type                            -- => underlying
                   PARAMtype      Length binder_ASTRef paramNum_Nat                 -- A reference to parameter # paramNum in lambda type `binder`
@@ -649,7 +650,7 @@ object TastyFormat {
     firstNatTreeTag <= tag && tag <= RENAMED ||
     firstASTTreeTag <= tag && tag <= BOUNDED ||
     firstNatASTTreeTag <= tag && tag <= NAMEDARG ||
-    firstLengthTreeTag <= tag && tag <= MATCHCASEtype ||
+    firstLengthTreeTag <= tag && tag <= FLEXIBLEtype ||
     tag == HOLE
 
   def isParamTag(tag: Int): Boolean = tag == PARAM || tag == TYPEPARAM
@@ -851,6 +852,7 @@ object TastyFormat {
     case MATCHCASEtype => "MATCHCASEtype"
     case MATCHtpt => "MATCHtpt"
     case PARAMtype => "PARAMtype"
+    case FLEXIBLEtype => "FLEXIBLEtype"
     case ANNOTATION => "ANNOTATION"
     case PRIVATEqualified => "PRIVATEqualified"
     case PROTECTEDqualified => "PROTECTEDqualified"