JVM_IR. Mostly remove descriptors from InterfaceLowering

Descriptors are only used to generate a new method name via a call to
KotlinTypeMapper.

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

@@ -153,10 +153,10 @@ fun IrClass.addSimpleDelegatingConstructor(
 val IrCall.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
 val IrFunctionReference.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
 
-
 fun IrValueParameter.copyTo(
     irFunction: IrFunction,
     shift: Int = 0,
+    index: Int? = null,
     startOffset: Int = this.startOffset,
     endOffset: Int = this.endOffset,
     origin: IrDeclarationOrigin = this.origin,
@@ -164,13 +164,16 @@ fun IrValueParameter.copyTo(
     type: IrType = this.type.remapTypeParameters(this.parent as IrTypeParametersContainer, irFunction),
     varargElementType: IrType? = this.varargElementType
 ): IrValueParameter {
+    // You cannot specify both index and nontrivial shift.
+    assert(index == null || shift == 0)
+    val newIndex = index ?: (shift + this.index)
     val descriptor = WrappedValueParameterDescriptor(symbol.descriptor.annotations, symbol.descriptor.source)
     val symbol = IrValueParameterSymbolImpl(descriptor)
     val defaultValueCopy = defaultValue?.deepCopyWithVariables()
     defaultValueCopy?.patchDeclarationParents(irFunction)
     return IrValueParameterImpl(
         startOffset, endOffset, origin, symbol,
-        name, shift + index, type, varargElementType, isCrossinline, isNoinline
+        name, newIndex, type, varargElementType, isCrossinline, isNoinline
     ).also {
         descriptor.bind(it)
         it.parent = irFunction