Add quick fixes for SMARTCAST_IMPOSSIBLE in 'if' #KT-27184 Fixed

idea/testData/quickfix/smartCastImpossibleInIfThen/ifThenElse5.kt

@@ -0,0 +1,13 @@
+// "Replace 'if' expression with elvis expression" "true"
+// WITH_RUNTIME
+class Test {
+    var x: Any? = null
+
+    fun test() {
+        val i = if (x is String) foo(<caret>x) else bar()
+    }
+
+    fun foo(s: String) = 1
+
+    fun bar() = 0
+}