Extract Function: Generate variables when boxing multiline expressions

idea/testData/refactoring/extractFunction/controlFlow/outputValues/nestedNonInlinableCall.kt.after

@@ -17,8 +17,9 @@ fun foo(a: Int): Int {
 
 private fun pair(a: Int, b: Int): Pair<Int, Int> {
     var b1 = b
-    return Pair(if (a > 0) {
+    val i = if (a > 0) {
         b1 += a
         a + 1
-    } else a, b1)
+    } else a
+    return Pair(i, b1)
 }

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValueWithExpression.kt.after

@@ -17,10 +17,11 @@ fun foo(a: Int): Int {
 
 private fun pair(a: Int, b: Int): Pair<Int, Int> {
     var b1 = b
-    return Pair(if (a > 0) {
+    val i = if (a > 0) {
         b1 += a
         b1
     } else {
         a
-    }, b1)
+    }
+    return Pair(i, b1)
 }

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValuesWithExpression.kt.after

@@ -22,11 +22,12 @@ fun foo(a: Int): Int {
 private fun triple(a: Int, b: Int, c: Int): Triple<Int, Int, Int> {
     var b1 = b
     var c1 = c
-    return Triple(if (a > 0) {
+    val i = if (a > 0) {
         b1 += a
         c1 -= b1
         b1
     } else {
         a
-    }, b1, c1)
+    }
+    return Triple(i, b1, c1)
 }