Make tests on -XXLanguage more tolerant to 1.2 -> 1.3 transition

compiler/testData/cli/jvm/internalArgEnableLanguageFeature.out

@@ -1,11 +1,13 @@
 warning: ATTENTION!
 This build uses internal compiler arguments:
 
--XXLanguage:+InlineClasses
+-XXLanguage:+SoundSmartCastsAfterTry
 
 This mode is strictly prohibited for production use,
 as no stability/compatibility guarantees are given on
 compiler or generated code. Use it at your own risk!
 
-warning: following manually enabled features will force generation of pre-release binaries: InlineClasses
-OK
+compiler/testData/cli/jvm/legacySmartCastsAfterTry.kt:8:9: error: only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type String?
+    some.length
+        ^
+COMPILATION_ERROR