Replace deprecated usages of max/min with maxOrNull/minOrNull

compiler/tests-common/tests/org/jetbrains/kotlin/cfg/AbstractPseudoValueTest.kt

@@ -79,9 +79,9 @@ abstract class AbstractPseudoValueTest : AbstractPseudocodeTest() {
             valueDescriptions[value to element] = valueDescription(element, value)
         }
 
-        val elementColumnWidth = elementToValues.keys.map { elementText(it).length }.max() ?: 1
-        val valueColumnWidth = allValues.map { valueDecl(it).length }.max()!!
-        val valueDescColumnWidth = valueDescriptions.values.map { it.length }.max()!!
+        val elementColumnWidth = elementToValues.keys.maxOfOrNull { elementText(it).length } ?: 1
+        val valueColumnWidth = allValues.maxOf { valueDecl(it).length }
+        val valueDescColumnWidth = valueDescriptions.values.maxOf { it.length }
 
         for ((ve, description) in valueDescriptions.entries) {
             val (value, element) = ve

compiler/tests-common/tests/org/jetbrains/kotlin/test/util/jetTestUtils.kt

@@ -23,7 +23,6 @@ import com.intellij.util.SmartFMap
 import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtPackageDirective
 import org.jetbrains.kotlin.psi.KtTreeVisitorVoid
-import java.io.File
 
 fun String.trimTrailingWhitespaces(): String =
     this.split('\n').joinToString(separator = "\n") { it.trimEnd() }
@@ -61,10 +60,6 @@ fun PsiFile.findElementsByCommentPrefix(prefix: String): Map<PsiElement, String>
     return result
 }
 
-fun findLastModifiedFile(dir: File, skipFile: (File) -> Boolean): File {
-    return dir.walk().filterNot(skipFile).maxBy { it.lastModified() }!!
-}
-
 val CodeInsightTestFixture.elementByOffset: PsiElement
     get() {
         return file.findElementAt(editor.caretModel.offset) ?: error("Can't find element at offset. Probably <caret> is missing.")