Remove NameOps' isErasedFunction

Co-authored-by: Nicolas Stucki <nicolas.stucki@gmail.com>

Author: natsukagami

compiler/src/dotty/tools/dotc/core/NameOps.scala

@@ -243,7 +243,6 @@ object NameOps {
       isFunctionPrefix(suffixStart, mustHave) && funArity(suffixStart) >= 0
 
     def isContextFunction(using Context): Boolean = isSpecificFunction("Context")
-    def isErasedFunction(using Context): Boolean = name eq tpnme.ErasedFunction
     def isImpureFunction(using Context): Boolean = isSpecificFunction("Impure")
 
     /** Is a synthetic function name, i.e. one of