[IR][refactoring] g/c IrReturnableBlock[Impl]

- drop calculatable from 'inlineFunctionSymbol' fields: 'sourceFileSymbol' and 'sourceFileName' and
replace then with extension values

- drop unused constructors.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/inline/FunctionInlining.kt

@@ -194,7 +194,7 @@ internal class FunctionInlining(val context: Context): IrElementTransformerVoidW
                 symbol = irReturnableBlockSymbol,
                 origin = if (isCoroutineIntrinsicCall) CoroutineIntrinsicLambdaOrigin else null,
                 statements = statements,
-                sourceFileSymbol = sourceFile.symbol
+                inlineFunctionSymbol = callee.symbol
             ).apply {
                 transformChildrenVoid(object : IrElementTransformerVoid() {
                     override fun visitReturn(expression: IrReturn): IrExpression {