Quick fix "add !!" for SMARTCAST_IMPOSSIBLE in certain situations

idea/testData/quickfix/typeMismatch/addExclExclWhenSmartCastImpossible.kt

@@ -0,0 +1,17 @@
+// "Add non-null asserted (!!) call" "true"
+// ACTION: Cast expression 'a' to 'Foo'
+
+interface Foo {
+    fun bar()
+}
+
+open class MyClass {
+    open val a: Foo? = null
+
+    fun foo() {
+        if (a != null) {
+            <caret>a.bar()
+        }
+    }
+}
+

idea/testData/quickfix/typeMismatch/addExclExclWhenSmartCastImpossible.kt.after

@@ -0,0 +1,17 @@
+// "Add non-null asserted (!!) call" "true"
+// ACTION: Cast expression 'a' to 'Foo'
+
+interface Foo {
+    fun bar()
+}
+
+open class MyClass {
+    open val a: Foo? = null
+
+    fun foo() {
+        if (a != null) {
+            a!!.bar()
+        }
+    }
+}
+