[JS IR BE] Use return type in function signature for inline classes

Bridge function should be created when return type of override function
is specialised to unboxed inline class. Thus return type should be used in
function signature.

Non-inline-class return types are not added to signature for interop and
infrastructure reasons ("toString" would become "toString_ret$kotlin_String")

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

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrNull
 import org.jetbrains.kotlin.ir.types.isUnit
+import org.jetbrains.kotlin.ir.util.isInlined
 import org.jetbrains.kotlin.ir.util.isInterface
 import org.jetbrains.kotlin.ir.util.isReal
 import org.jetbrains.kotlin.ir.util.parentAsClass
@@ -188,13 +189,15 @@ class FunctionAndSignature(val function: IrSimpleFunction) {
     private data class Signature(
         val name: Name,
         val extensionReceiverType: String?,
-        val valueParameters: List<String?>
+        val valueParameters: List<String?>,
+        val returnType: String?
     )
 
     private val signature = Signature(
         function.name,
         function.extensionReceiverParameter?.type?.asString(),
-        function.valueParameters.map { it.type.asString() }
+        function.valueParameters.map { it.type.asString() },
+        function.returnType.run { if (isInlined()) asString() else null }
     )
 
     override fun equals(other: Any?): Boolean {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/SimpleNameGenerator.kt

@@ -13,8 +13,10 @@ import org.jetbrains.kotlin.ir.expressions.IrLoop
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrFail
+import org.jetbrains.kotlin.ir.types.isUnit
 import org.jetbrains.kotlin.ir.util.isDynamic
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
+import org.jetbrains.kotlin.ir.util.isInlined
 import org.jetbrains.kotlin.js.backend.ast.JsName
 import org.jetbrains.kotlin.js.naming.isES5IdentifierPart
 import org.jetbrains.kotlin.js.naming.isES5IdentifierStart
@@ -201,6 +203,11 @@ class SimpleNameGenerator : NameGenerator {
                     declaration.valueParameters.ifNotEmpty {
                         joinTo(nameBuilder, "") { "_${it.type.asString()}" }
                     }
+                    declaration.returnType.let {
+                        if (it.isInlined()) {
+                            nameBuilder.append("_ret$${it.asString()}")
+                        }
+                    }
                 }
 
             }