KT-3750 When without else

#KT-3750 Fixed

idea/testData/codeInsight/outOfBlock/InGlobalPropertyWithGetter.kt

@@ -0,0 +1,9 @@
+// FALSE
+class B(val a: A)
+val B.foo: Int
+    get() {
+        return <caret>when (a) {
+            A.e1 -> 1
+            A.e2 -> 4
+        }
+    }