Make statement containers mutable.

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBody.kt

@@ -30,11 +30,7 @@ interface IrExpressionBody : IrBody {
 }
 
 interface IrStatementContainer {
-    val statements: List<IrStatement>
-
-    fun addStatement(statement: IrStatement)
-    fun addAll(statements: Collection<IrStatement>)
-    fun putStatement(index: Int, statement: IrStatement)
+    val statements: MutableList<IrStatement>
 }
 
 interface IrBlockBody : IrBody, IrStatementContainer

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt

@@ -25,18 +25,6 @@ import java.util.*
 class IrBlockBodyImpl(startOffset: Int, endOffset: Int) : IrElementBase(startOffset, endOffset), IrBlockBody {
     override val statements: MutableList<IrStatement> = ArrayList()
 
-    override fun addStatement(statement: IrStatement) {
-        statements.add(statement)
-    }
-
-    override fun addAll(statements: Collection<IrStatement>) {
-        this.statements.addAll(statements)
-    }
-
-    override fun putStatement(index: Int, statement: IrStatement) {
-        statements[index] = statement
-    }
-
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R {
         return visitor.visitBlockBody(this, data)
     }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockImpl.kt

@@ -27,7 +27,7 @@ class IrBlockImpl(startOffset: Int, endOffset: Int, type: KotlinType, origin: Ir
         IrContainerExpressionBase(startOffset, endOffset, type, origin), IrBlock {
     constructor(startOffset: Int, endOffset: Int, type: KotlinType, origin: IrStatementOrigin?, statements: List<IrStatement>) :
             this(startOffset, endOffset, type, origin) {
-        addAll(statements)
+        this.statements.addAll(statements)
     }
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
@@ -45,14 +45,14 @@ class IrBlockImpl(startOffset: Int, endOffset: Int, type: KotlinType, origin: Ir
 }
 
 fun IrBlockImpl.addIfNotNull(statement: IrStatement?) {
-    if (statement != null) addStatement(statement)
+    if (statement != null) statements.add(statement)
 }
 
 fun IrBlockImpl.inlineStatement(statement: IrStatement) {
     if (statement is IrBlock) {
-        addAll(statement.statements)
+        statements.addAll(statement.statements)
     }
     else {
-        addStatement(statement)
+        statements.add(statement)
     }
 }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrCompositeImpl.kt

@@ -27,7 +27,7 @@ class IrCompositeImpl(startOffset: Int, endOffset: Int, type: KotlinType, origin
         IrContainerExpressionBase(startOffset, endOffset, type, origin), IrComposite {
     constructor(startOffset: Int, endOffset: Int, type: KotlinType, origin: IrStatementOrigin?, statements: List<IrStatement>) :
             this(startOffset, endOffset, type, origin) {
-        addAll(statements)
+        this.statements.addAll(statements)
     }
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrContainerExpressionBase.kt

@@ -28,18 +28,6 @@ abstract class IrContainerExpressionBase(startOffset: Int, endOffset: Int, type:
         IrExpressionBase(startOffset, endOffset, type), IrContainerExpression {
     override val statements: MutableList<IrStatement> = ArrayList(2)
 
-    override fun addStatement(statement: IrStatement) {
-        statements.add(statement)
-    }
-
-    override fun addAll(statements: Collection<IrStatement>) {
-        this.statements.addAll(statements)
-    }
-
-    override fun putStatement(index: Int, statement: IrStatement) {
-        statements[index] = statement
-    }
-
     override fun <D> acceptChildren(visitor: IrElementVisitor<Unit, D>, data: D) {
         statements.forEach { it.accept(visitor, data) }
     }