Hide stageController into the IrFactory

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/Lower.kt

@@ -19,8 +19,10 @@ package org.jetbrains.kotlin.backend.common
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.expressions.IrBlockBody
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.expressions.IrStatementContainer
+import org.jetbrains.kotlin.ir.expressions.IrExpressionBody
 import org.jetbrains.kotlin.ir.util.transformFlat
 import org.jetbrains.kotlin.ir.util.transformSubsetFlat
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
@@ -151,8 +153,8 @@ private class BodyLoweringVisitor(
         if (allowDeclarationModification) {
             loweringPass.lower(body, data!!)
         } else {
-            stageController.bodyLowering {
-                loweringPass.lower(body, data!!)
+            data!!.factory.stageController.bodyLowering {
+                loweringPass.lower(body, data)
             }
         }
     }
@@ -178,7 +180,7 @@ interface DeclarationTransformer : FileLoweringPass {
     }
 
     private fun transformFlatRestricted(declaration: IrDeclaration): List<IrDeclaration>? {
-        return stageController.restrictTo(declaration) {
+        return declaration.factory.stageController.restrictTo(declaration) {
             transformFlat(declaration)
         }
     }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -355,7 +355,7 @@ fun IrType.remapTypeParameters(
 
 /* Copied from K/N */
 fun IrDeclarationContainer.addChild(declaration: IrDeclaration) {
-    stageController.unrestrictDeclarationListsAccess {
+    declaration.factory.stageController.unrestrictDeclarationListsAccess {
         this.declarations += declaration
     }
     declaration.setDeclarationsParent(this)

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InnerClassesLowering.kt

@@ -35,7 +35,7 @@ class InnerClassesLowering(val context: BackendContext, private val innerClasses
 
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
         if (declaration is IrClass && declaration.isInner) {
-            stageController.unrestrictDeclarationListsAccess {
+            context.irFactory.stageController.unrestrictDeclarationListsAccess {
                 declaration.declarations += innerClassesSupport.getOuterThisField(declaration)
             }
         } else if (declaration is IrConstructor) {