Fix issue 6403: do not crash if super indexed load does not exist (return 'no-such-method call' ins…

tests/language/super_operator_test.dart

Index: tests/language/super_operator_test.dart
===================================================================
--- tests/language/super_operator_test.dart	(revision 14288)
+++ tests/language/super_operator_test.dart	(working copy)
@@ -47,6 +47,18 @@
 
 }
 
+
+class Autobianchi {
+  g() => super[0];
+}
+
+
+testRegression6403() {
+  // Do not crash, throw exception instead
+  new Autobianchi().g();
+}
+
+
 main () {
   var a = new A();
   a = a + "William";  // operator + of class A.
@@ -62,4 +74,5 @@
   Expect.equals(43, a.things[4]);
   Expect.equals(86, a[4]);
 
+  Expect.throws(testRegression6403);
 }