Remove dependency of ir.serialization.common on ir.backend.common

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

@@ -697,7 +697,3 @@ fun IrExpression?.isPure(
 
     return false
 }
-
-fun IrDeclaration.isFromJava(): Boolean =
-    origin == IrDeclarationOrigin.IR_EXTERNAL_JAVA_DECLARATION_STUB ||
-            parent is IrDeclaration && (parent as IrDeclaration).isFromJava()

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

@@ -23,8 +23,6 @@ import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
 interface InnerClassesSupport {
-    object FIELD_FOR_OUTER_THIS : IrDeclarationOriginImpl("FIELD_FOR_OUTER_THIS", isSynthetic = true)
-
     fun getOuterThisField(innerClass: IrClass): IrField
     fun getInnerClassConstructorWithOuterThisParameter(innerClassConstructor: IrConstructor): IrConstructor
     fun getInnerClassOriginalPrimaryConstructorOrNull(innerClass: IrClass): IrConstructor?