Remove obsolete and unused descriptors and utils

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/IrBuiltIns.kt

@@ -127,7 +127,6 @@ class IrBuiltIns(
 
     val collectionClass = builtIns.collection.toIrSymbol()
 
-    val arrayType = builtIns.array.toIrType(symbolTable = symbolTable)
     val arrayClass = builtIns.array.toIrSymbol()
 
     val throwableType = builtIns.throwable.defaultType.toIrType()

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/irTypes.kt

@@ -107,11 +107,6 @@ private fun makeKotlinType(
     return classifier.descriptor.defaultType.replace(newArguments = kotlinTypeArguments).makeNullableAsSpecified(hasQuestionMark)
 }
 
-fun ClassifierDescriptor.toIrType(hasQuestionMark: Boolean = false, symbolTable: SymbolTable? = null): IrType {
-    val symbol = getSymbol(symbolTable)
-    return IrSimpleTypeImpl(defaultType, symbol, hasQuestionMark, listOf(), listOf())
-}
-
 val IrTypeParameter.defaultType: IrType
     get() = IrSimpleTypeImpl(
         symbol,
@@ -155,4 +150,4 @@ private fun ClassifierDescriptor.getSymbol(symbolTable: SymbolTable?): IrClassif
     is ClassDescriptor -> symbolTable?.referenceClass(this) ?: IrClassSymbolImpl(this)
     is TypeParameterDescriptor -> symbolTable?.referenceTypeParameter(this) ?: IrTypeParameterSymbolImpl(this)
     else -> TODO()
-}
+}