KT-34582 Exclude kotlin.coroutines.experimental package from completion and auto-import

- Exclusion happens only when `ReleaseCoroutines` feature is supported
- Add `LANGUAGE_VERSION` to few tests to make sure that previous exclusions still work when `experimental` package is not excluded entirely
- ^KT-34582 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/core/excludedFromImportsAndCompletion.kt

@@ -7,8 +7,10 @@ package org.jetbrains.kotlin.idea.core
 
 import com.intellij.codeInsight.JavaProjectCodeInsightSettings
 import com.intellij.openapi.project.Project
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.idea.imports.importableFqName
+import org.jetbrains.kotlin.idea.project.languageVersionSettings
 import org.jetbrains.kotlin.psi.KtFile
 
 
@@ -25,8 +27,19 @@ private val exclusions =
 private fun shouldBeHiddenAsInternalImplementationDetail(fqName: String, locationFqName: String) =
     exclusions.any { fqName.startsWith(it) } && (locationFqName.isBlank() || !fqName.startsWith(locationFqName))
 
+/**
+ * We do not want to show nothing from "kotlin.coroutines.experimental" when release coroutines are available,
+ * since in 1.3 this package is obsolete.
+ *
+ * However, we still want to show this package when release coroutines are not available.
+ */
+private fun usesOutdatedCoroutinesPackage(fqName: String, inFile: KtFile): Boolean =
+    fqName.startsWith("kotlin.coroutines.experimental.") &&
+            inFile.languageVersionSettings.supportsFeature(LanguageFeature.ReleaseCoroutines)
+
 fun DeclarationDescriptor.isExcludedFromAutoImport(project: Project, inFile: KtFile?): Boolean {
     val fqName = importableFqName?.asString() ?: return false
     return JavaProjectCodeInsightSettings.getSettings(project).isExcluded(fqName) ||
+            (inFile != null && usesOutdatedCoroutinesPackage(fqName, inFile)) ||
             shouldBeHiddenAsInternalImplementationDetail(fqName, inFile?.packageFqName?.asString() ?: "")
 }