[K/Wasm] Introduce stepping tests for Wasm

compiler/testData/debug/stepping/simpleDefaultArg.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: WASM
 // FILE: test.kt
 
 fun ifoo(ok: String = "OK"): String {
@@ -10,11 +11,11 @@ fun box(): String {
 
 // FORCE_STEP_INTO
 // EXPECTATIONS JVM JVM_IR
-// test.kt:8 box
-// test.kt:3 ifoo$default (synthetic)
-// test.kt:4 ifoo
-// test.kt:3 ifoo$default (synthetic)
-// test.kt:8 box
+// test.kt:9 box
+// test.kt:4 ifoo$default (synthetic)
+// test.kt:5 ifoo
+// test.kt:4 ifoo$default (synthetic)
+// test.kt:9 box
 
 // EXPECTATIONS JS_IR
-// test.kt:8 box
+// test.kt:9 box