[IR generator] Use Element#typeName i/o Element#name where needed

This slightly reduces repetition.

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt

@@ -16,8 +16,9 @@ import org.jetbrains.kotlin.generators.tree.printer.printFunctionWithBlockBody
 import org.jetbrains.kotlin.ir.generator.config.AbstractTreeBuilder
 import org.jetbrains.kotlin.ir.generator.model.Element
 import org.jetbrains.kotlin.ir.generator.model.Element.Category.*
-import org.jetbrains.kotlin.ir.generator.model.Element.Companion.elementName2typeName
 import org.jetbrains.kotlin.ir.generator.model.ListField.Mutability.*
+import org.jetbrains.kotlin.ir.generator.model.ListField.Mutability.Array
+import org.jetbrains.kotlin.ir.generator.model.ListField.Mutability.List
 import org.jetbrains.kotlin.ir.generator.model.SingleField
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -141,11 +142,11 @@ object IrTree : AbstractTreeBuilder() {
             kDoc = """
             The arbitrary metadata associated with this IR node.
             
-            @see ${elementName2typeName(this@element.name)}
+            @see $typeName
             """.trimIndent()
         }
         kDoc = """
-        An [${elementName2typeName(rootElement.name)}] capable of holding something which backends can use to write
+        An [${rootElement.typeName}] capable of holding something which backends can use to write
         as the metadata for the declaration.
         
         Technically, it can even be ± an array of bytes, but right now it's usually the frontend representation of the declaration,
@@ -224,7 +225,7 @@ object IrTree : AbstractTreeBuilder() {
             fun foo(defined: Int, ${'$'}extra: String) { /* ... */ }
             ```
 
-            If a compiler plugin adds parameters to an [${elementName2typeName(function.name)}],
+            If a compiler plugin adds parameters to an [${function.typeName}],
             the representations of the function in the frontend and in the backend may diverge, potentially causing signature mismatch and
             linkage errors (see [KT-40980](https://youtrack.jetbrains.com/issue/KT-40980)).
             We wouldn't want IR plugins to affect the frontend representation, since in an IDE you'd want to be able to see those
@@ -299,7 +300,7 @@ object IrTree : AbstractTreeBuilder() {
             If this is a sealed class or interface, this list contains symbols of all its immediate subclasses.
             Otherwise, this is an empty list.
             
-            NOTE: If this [${elementName2typeName(this@element.name)}] was deserialized from a klib, this list will always be empty!
+            NOTE: If this [$typeName] was deserialized from a klib, this list will always be empty!
             See [KT-54028](https://youtrack.jetbrains.com/issue/KT-54028).
             """.trimIndent()
         }

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/model/Model.kt

@@ -68,7 +68,7 @@ class Element(
     override var kind: ImplementationKind? = null
 
     override val typeName
-        get() = elementName2typeName(name)
+        get() = "Ir" + name.replaceFirstChar(Char::uppercaseChar)
 
     /**
      * Whether this element is semantically a leaf element in the hierarchy.
@@ -113,10 +113,6 @@ class Element(
 
     override fun toString() = name
 
-    companion object {
-        fun elementName2typeName(name: String) = "Ir" + name.replaceFirstChar(Char::uppercaseChar)
-    }
-
     fun elementParentsRecursively(): List<ElementRef> {
         val linkedSet = buildSet {
             fun recurse(element: Element) {

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/print/VisitorsAndTransformers.kt

@@ -133,7 +133,7 @@ private class TransformerVoidPrinter(
 
     // IrPackageFragment is treated as transformByChildren in IrElementTransformerVoid for historical reasons.
     private val Element.isPackageFragment: Boolean
-        get() = name == IrTree.packageFragment.name
+        get() = this == IrTree.packageFragment
 
     // Despite IrFile and IrExternalPackageFragment being transformByChildren, we treat them differently in IrElementTransformerVoid
     // than in IrElementTransformer for historical reasons. We want to preserve the historical semantics here.
@@ -325,11 +325,11 @@ private class TypeTransformerPrinter(
             }
 
             printBlock {
-                when (element.name) {
-                    IrTree.memberAccessExpression.name -> {
+                when (element) {
+                    IrTree.memberAccessExpression -> {
                         if (irTypeFields.singleOrNull()?.name != "typeArguments") {
                             error(
-                                """`Ir${IrTree.memberAccessExpression.name.capitalizeAsciiOnly()}` has unexpected fields with `IrType` type. 
+                                """`${IrTree.memberAccessExpression.typeName}` has unexpected fields with `IrType` type. 
                                         |Please adjust logic of `${visitorType.simpleName}`'s generation.""".trimMargin()
                             )
                         }
@@ -348,7 +348,7 @@ private class TypeTransformerPrinter(
                         }
                         println("}")
                     }
-                    IrTree.`class`.name -> {
+                    IrTree.`class` -> {
                         println(visitorParam, ".valueClassRepresentation?.mapUnderlyingType {")
                         withIndent {
                             println("transformType(", visitorParam, ", it, data)")