[Gradle, JS] Add attribute for IR target

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinTargetConfigurator.kt

@@ -29,7 +29,9 @@ import org.jetbrains.kotlin.gradle.dsl.KotlinCommonOptions
 import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.plugin.mpp.*
 import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget
+import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget.Companion.IR
 import org.jetbrains.kotlin.gradle.targets.js.KotlinJsTarget.Companion.LEGACY
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
 import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
 import java.util.concurrent.Callable
 import kotlin.reflect.KMutableProperty1
@@ -451,6 +453,10 @@ fun Configuration.usesPlatformOf(target: KotlinTarget): Configuration {
         attributes.attribute(KotlinJsTarget.jsLegacyAttribute, LEGACY)
     }
 
+    if (target is KotlinJsIrTarget) {
+        attributes.attribute(KotlinJsTarget.jsLegacyAttribute, IR)
+    }
+
     // TODO: Provide an universal way to copy attributes from the target.
     if (target is KotlinNativeTarget) {
         attributes.attribute(KotlinNativeTarget.konanTargetAttribute, target.konanTarget.name)

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/KotlinJsCompilation.kt

@@ -34,7 +34,7 @@ open class KotlinJsCompilation(
 
     override val defaultSourceSetName: String
         get() = lowerCamelCaseName(
-            target.disambiguationClassifier?.removePrefix(LEGACY_DISAMBIGUATION_CLASSIFIER),
+            target.disambiguationClassifier?.removePrefix(LEGACY_DISAMBIGUATION_CLASSIFIER)?.toLowerCase(),
             compilationName
         )
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/KotlinJsTarget.kt

@@ -182,6 +182,7 @@ constructor(
         )
 
         const val LEGACY = "legacy"
+        const val IR = "ir"
 
         fun setupAttributesMatchingStrategy(attributesSchema: AttributesSchema) {
             attributesSchema.attribute(jsLegacyAttribute)