Introduce an API to convert TypeConstructorMarker to TypeParameterMarker

compiler/backend.common.jvm/src/org/jetbrains/kotlin/types/AbstractTypeMapper.kt

@@ -122,7 +122,7 @@ object AbstractTypeMapper {
             }
 
             typeConstructor.isTypeParameter() -> {
-                val typeParameter = typeConstructor as TypeParameterMarker
+                val typeParameter = typeConstructor.asTypeParameter()
                 return mapType(context, typeParameter.representativeUpperBound(), mode, null).also { asmType ->
                     sw?.writeTypeVariable(typeParameter.getName(), asmType)
                 }

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirJvmTypeMapper.kt

@@ -207,6 +207,11 @@ class ConeTypeSystemCommonBackendContextForTypeMapping(
         return this is ConeTypeParameterLookupTag
     }
 
+    override fun TypeConstructorMarker.asTypeParameter(): TypeParameterMarker {
+        require(isTypeParameter())
+        return this as ConeTypeParameterLookupTag
+    }
+
     override fun TypeConstructorMarker.defaultType(): ConeSimpleKotlinType {
         require(this is ConeClassifierLookupTag)
         return when (this) {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/IrTypeMapper.kt

@@ -223,6 +223,11 @@ private class IrTypeCheckerContextForTypeMapping(
         return this is IrTypeParameterSymbol
     }
 
+    override fun TypeConstructorMarker.asTypeParameter(): TypeParameterMarker {
+        require(isTypeParameter())
+        return this as IrTypeParameterSymbol
+    }
+
     override fun TypeConstructorMarker.defaultType(): IrType {
         return when (this) {
             is IrClassSymbol -> owner.defaultType