Debugger: more precise context expression in codeFragment

#KT-11380 Fixed

idea/testData/debugger/tinyApp/src/evaluate/multipleBreakpoints/smartcasts.kt

@@ -0,0 +1,35 @@
+package smartcasts
+
+fun main(args: Array<String>) {
+    test1(Derived())
+    test1(Base())
+
+    test2(Derived())
+    test2(null)
+}
+
+// EXPRESSION: derived.prop
+// RESULT: 1: I
+
+// EXPRESSION: derived.prop
+// RESULT: java.lang.ClassCastException: smartcasts.Base cannot be cast to smartcasts.Derived: Ljava/lang/ClassCastException;
+fun test1(derived: Base) =
+        derived is Derived &&
+        //Breakpoint!
+        derived.prop == 1
+
+// EXPRESSION: nullable.prop
+// RESULT: 1: I
+
+// EXPRESSION: nullable.prop
+// RESULT: Method threw 'kotlin.TypeCastException' exception.
+fun test2(nullable: Derived?) =
+        nullable != null &&
+        //Breakpoint!
+        nullable.prop == 1
+
+class Derived : Base() {
+    val prop = 1
+}
+
+open class Base