use CharSequence methods where available (KOTLIN-CR-2456)

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/PerModulePackageCacheService.kt

@@ -66,7 +66,7 @@ class KotlinPackageContentModificationListener(private val project: Project) {
                         .filter(::isRelevant)
                         .filter {
                             val vFile = it.file!!
-                            vFile.isDirectory || FileTypeRegistry.getInstance().getFileTypeByFileName(vFile.name) == KotlinFileType.INSTANCE
+                            vFile.isDirectory || FileTypeRegistry.getInstance().getFileTypeByFileName(vFile.nameSequence) == KotlinFileType.INSTANCE
                         }
                         .forEach { event -> service.notifyPackageChange(event) }
                 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/util/ProjectRootsUtil.kt

@@ -121,7 +121,7 @@ object ProjectRootsUtil {
         if (!includeLibraryClasses && !includeLibrarySource) return false
 
         // NOTE: the following is a workaround for cases when class files are under library source roots and source files are under class roots
-        val fileType = FileTypeManager.getInstance().getFileTypeByFileName(file.name)
+        val fileType = FileTypeManager.getInstance().getFileTypeByFileName(file.nameSequence)
         val canContainClassFiles = fileType == ArchiveFileType.INSTANCE || file.isDirectory
         val isBinary = fileType.isKotlinBinary()