Added tests for obsolete tasks

compiler/testData/diagnostics/testsWithStdLib/inference/kt3458.kt

@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+import java.io.File
+
+fun test() {
+    val dir = File("dir")
+    val files = dir.listFiles()?.toList() ?: listOf() // error
+    files checkType { _<List<File>>() }
+}

compiler/testData/diagnostics/testsWithStdLib/inference/kt3458.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(): kotlin.Unit

compiler/testData/diagnostics/testsWithStdLib/inference/kt4975.kt

@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+fun <T> bar(f: () -> T) : T = f()
+
+fun test(map: MutableMap<Int, Int>) {
+    val r = bar {
+        map[1] = 2
+    }
+    r checkType { _<Unit>() }
+}

compiler/testData/diagnostics/testsWithStdLib/inference/kt4975.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun </*0*/ T> bar(/*0*/ f: () -> T): T
+internal fun test(/*0*/ map: kotlin.MutableMap<kotlin.Int, kotlin.Int>): kotlin.Unit