K2: drop unused ConeStubTypeForSyntheticFixation

compiler/fir/cones/src/org/jetbrains/kotlin/fir/renderer/ConeTypeRenderer.kt

@@ -120,10 +120,6 @@ open class ConeTypeRenderer(
                 builder.append(")")
             }
 
-            is ConeStubTypeForSyntheticFixation -> {
-                builder.append("Stub (fixation): ${type.constructor.variable}")
-            }
-
             is ConeStubTypeForChainInference -> {
                 builder.append("Stub (chain inference): ${type.constructor.variable}")
             }

compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypeVariableAndStubTypes.kt

@@ -103,11 +103,6 @@ open class ConeStubTypeForChainInference(
     )
 }
 
-class ConeStubTypeForSyntheticFixation(
-    constructor: ConeStubTypeConstructor,
-    nullability: ConeNullability
-) : ConeStubTypeForChainInference(constructor, nullability)
-
 class ConeStubTypeForTypeVariableInSubtyping(
     constructor: ConeStubTypeConstructor,
     nullability: ConeNullability

compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt

@@ -215,7 +215,6 @@ fun <T : ConeKotlinType> T.withNullability(
             ConeNullability.NOT_NULL -> this
         }
 
-        is ConeStubTypeForSyntheticFixation -> ConeStubTypeForSyntheticFixation(constructor, nullability)
         is ConeStubTypeForChainInference -> ConeStubTypeForChainInference(constructor, nullability)
         is ConeStubTypeForTypeVariableInSubtyping -> ConeStubTypeForTypeVariableInSubtyping(constructor, nullability)
         is ConeDefinitelyNotNullType -> when (nullability) {