Drop isErrorTypeAllowed flag from type system context

The flag was used exclusively during calculation of common super type.
This change relies on assumption, that common super type is
NOT calculated in IR type system context.

core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt

@@ -33,8 +33,6 @@ import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.contract
 
 interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSystemCommonBackendContext {
-    override val isErrorTypeAllowed: Boolean get() = false
-
     override fun TypeConstructorMarker.isDenotable(): Boolean {
         require(this is TypeConstructor, this::errorMessage)
         return this.isDenotable

core/type-system/src/org/jetbrains/kotlin/types/model/TypeSystemContext.kt

@@ -78,10 +78,6 @@ interface TypeCheckerProviderContext {
 }
 
 interface TypeSystemCommonSuperTypesContext : TypeSystemContext, TypeSystemTypeFactoryContext, TypeCheckerProviderContext {
-    /*
-     * If set in false then if there is an error supertype in input types list of `commonSuperType` it will be returned
-     */
-    val isErrorTypeAllowed: Boolean
 
     fun KotlinTypeMarker.anySuperTypeConstructor(predicate: (TypeConstructorMarker) -> Boolean) =
         newBaseTypeCheckerContext(errorTypesEqualToAnything = false, stubTypesEqualToAnything = true)