[Wasm] Don't use by lazy inside Throwable

compiler/testData/codegen/box/size/add.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 72_224 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 66_687 
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_517 
 
 // FILE: test.kt

compiler/testData/codegen/box/size/helloWorld.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 72_549 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 67_012 
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_458 
 
 fun box(): String {

compiler/testData/codegen/box/size/helloWorldDOM.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 84_364 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 78_710 
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_956 
 
 // FILE: test.kt

compiler/testData/codegen/box/size/ok.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 72_275 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 66_738 
 // WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_389 
 
 fun box() = "OK"

libraries/stdlib/wasm/builtins/kotlin/Throwable.kt

@@ -24,9 +24,14 @@ public open class Throwable(open val message: String?, open val cause: kotlin.Th
 
     private val jsStack: ExternalInterfaceType = captureStackTrace()
 
-    internal val stack: String by lazy {
+    private lateinit var _stack: String
-        jsToKotlinStringAdapter(jsStack).removePrefix("Error\n")
+    internal val stack: String
-    }
+        get() {
+            if (!::_stack.isInitialized) {
+                _stack = jsToKotlinStringAdapter(jsStack).removePrefix("Error\n")
+            }
+            return _stack
+        }
 
     internal var suppressedExceptionsList: MutableList<Throwable>? = null