Properly disable tests on WASM. (#3665)

backend.native/tests/build.gradle

@@ -2249,8 +2249,8 @@ task indexof(type: KonanLocalTest) {
 
 task utf8(type: KonanLocalTest) {
     // Cannot be executed in the two-stage mode due to KT-33175.
-    enabled = !twoStageEnabled
-    expectedFail = (project.testTarget == 'wasm32') // Uses exceptions.
+    // Uses exceptions so cannot run on wasm.
+    enabled = !twoStageEnabled && (project.testTarget != 'wasm32')
     goldValue = "Hello\nПривет\n\uD800\uDC00\n\n\uFFFD\uFFFD\n\uFFFD12\n\uFFFD12\n12\uFFFD\n\uD83D\uDE25\n\uD83D\uDE25\n\uD83D\uDE25\n"
     source = "runtime/text/utf8.kt"
 }
@@ -2723,7 +2723,7 @@ standaloneTest("memory_only_gc") {
 }
 
 standaloneTest("leak_detector") {
-    disabled = project.globalTestArgs.contains('-opt')
+    disabled = project.globalTestArgs.contains('-opt') || (project.testTarget == 'wasm32') // Needs debug build.
     flags = ['-g']
     source = "runtime/memory/leak_detector.kt"
 }