[JS IR] Emit original names for local vars to sourcemaps

#KT-35655 Fixed

compiler/testData/debug/jsTestHelpers/jsCommonTestHelpers.kt

@@ -0,0 +1,66 @@
+// This file is compiled into each stepping test.
+
+package testUtils
+
+import kotlin.coroutines.Continuation
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+
+external interface ValueDescriptionForSteppingTests {
+    var isNull: Boolean?
+    var isReferenceType: Boolean?
+    var valueDescription: String?
+    var typeName: String?
+}
+
+external object JSON {
+    fun stringify(o: Any?): String
+}
+
+/**
+ * This function is only called from the debugger
+ */
+@JsExport
+fun makeValueDescriptionForSteppingTests(value: Any?): ValueDescriptionForSteppingTests? {
+    val jsTypeName = jsTypeOf(value)
+    val displayedTypeName = when (jsTypeName) {
+        "undefined" -> return null
+        "string", "object", "function" -> if (value == null) jsTypeName else {
+            val klass = value::class
+            // Fully qualified names are not yet supported in Kotlin/JS reflection
+            knownFqNames[klass] ?: klass.simpleName ?: "<anonymous>"
+        }
+        else -> jsTypeName
+    }
+    return js("{}").unsafeCast<ValueDescriptionForSteppingTests>().apply {
+        isNull = value == null
+        isReferenceType = jsTypeName == "object" || jsTypeName == "function"
+        valueDescription = when (jsTypeName) {
+            "string" -> JSON.stringify(value)
+            else -> value.toString()
+        }
+        typeName = displayedTypeName
+    }
+}
+
+private val minimalFqNames = mapOf(
+    Long::class to "kotlin.Long",
+    String::class to "kotlin.String",
+    Array::class to "kotlin.Array",
+    RuntimeException::class to "kotlin.RuntimeException",
+    ArithmeticException::class to "kotlin.ArithmeticException",
+)
+
+private val knownFqNames = minimalFqNames + stdlibFqNames
+
+private object EmptyContinuation: Continuation<Any?> {
+    override val context: CoroutineContext
+        get() = EmptyCoroutineContext
+
+    override fun resumeWith(result: Result<Any?>) {
+        result.getOrThrow()
+    }
+}
+
+@JsExport
+fun makeEmptyContinuation(): dynamic = EmptyContinuation