FIR: unify common special names scattered around the code base

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

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.ir.types.impl.*
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.resolve.descriptorUtil.isEffectivelyExternal
 import org.jetbrains.kotlin.resolve.scopes.DescriptorKindFilter
 import org.jetbrains.kotlin.types.KotlinType
@@ -259,7 +260,7 @@ class IrDescriptorBasedFunctionFactory(
             buildSimpleType()
         }
         val vDeclaration = irFactory.createValueParameter(
-            offset, offset, classOrigin, vSymbol, Name.special("<this>"), -1, type, null,
+            offset, offset, classOrigin, vSymbol, SpecialNames.THIS, -1, type, null,
             isCrossinline = false,
             isNoinline = false,
             isHidden = false,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/AdditionalIrUtils.kt

@@ -58,12 +58,10 @@ val IrClass.classId: ClassId?
 val IrDeclaration.nameForIrSerialization: Name
     get() = when (this) {
         is IrDeclarationWithName -> this.name
-        is IrConstructor -> SPECIAL_INIT_NAME
+        is IrConstructor -> SpecialNames.INIT
         else -> error(this)
     }
 
-private val SPECIAL_INIT_NAME = Name.special("<init>")
-
 val IrValueParameter.isVararg get() = this.varargElementType != null
 
 val IrFunction.isSuspend get() = this is IrSimpleFunction && this.isSuspend