Invert LanguageFeature responsible for warning on coroutines

The problem was that LanguageVersionSettingsImpl.DEFAULT did not have
"WarnOnCoroutines" as a feature and so it was manually added to the settings,
but only in two places: in the compiler and in the IDE

compiler/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsTestWithJsStdLib.kt

@@ -62,11 +62,10 @@ abstract class AbstractDiagnosticsTestWithJsStdLib : AbstractDiagnosticsTest() {
             moduleContext: ModuleContext,
             files: List<KtFile>,
             moduleTrace: BindingTrace,
-            languageVersionSettings: LanguageVersionSettings?,
+            languageVersionSettings: LanguageVersionSettings,
             separateModules: Boolean
     ): JsAnalysisResult {
         // TODO: support LANGUAGE directive in JS diagnostic tests
-        assert(languageVersionSettings == null) { "$LANGUAGE_DIRECTIVE directive is not supported in JS diagnostic tests" }
         moduleTrace.record<ModuleDescriptor, ModuleKind>(MODULE_KIND, moduleContext.module, getModuleKind(files))
         return TopDownAnalyzerFacadeForJS.analyzeFilesWithGivenTrace(files, moduleTrace, moduleContext, config)
     }

compiler/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsTestWithJsStdLibAndBackendCompilation.kt

@@ -30,7 +30,7 @@ abstract class AbstractDiagnosticsTestWithJsStdLibAndBackendCompilation : Abstra
             moduleContext: ModuleContext,
             files: List<KtFile>,
             moduleTrace: BindingTrace,
-            languageVersionSettings: LanguageVersionSettings?,
+            languageVersionSettings: LanguageVersionSettings,
             separateModules: Boolean
     ): JsAnalysisResult {
         val analysisResult = super.analyzeModuleContents(moduleContext, files, moduleTrace, languageVersionSettings, separateModules)