Refactor visitSendSet for super compounds and assignment.

pkg/compiler/lib/src/types/type_mask.dart

Index: pkg/compiler/lib/src/types/type_mask.dart
diff --git a/pkg/compiler/lib/src/types/type_mask.dart b/pkg/compiler/lib/src/types/type_mask.dart
index bf095b860dbf609ef9cc5367f1a3cc661ad203ef..9ea82abea67e04a7d90e41ba9c98ee9149cd2a5e 100644
--- a/pkg/compiler/lib/src/types/type_mask.dart
+++ b/pkg/compiler/lib/src/types/type_mask.dart
@@ -22,7 +22,7 @@ abstract class TypeMask {
 
   factory TypeMask.exact(ClassElement base, ClassWorld classWorld) {
     assert(invariant(base, classWorld.isInstantiated(base),
-        message: "Cannot create extact type mask for uninstantiated class "
+        message: "Cannot create exact type mask for uninstantiated class "
           "${base.name}"));
     return new FlatTypeMask.exact(base);
   }
@@ -55,7 +55,7 @@ abstract class TypeMask {
 
   factory TypeMask.nonNullExact(ClassElement base, ClassWorld classWorld) {
     assert(invariant(base, classWorld.isInstantiated(base),
-        message: "Cannot create extact type mask for "
+        message: "Cannot create exact type mask for "
                  "uninstantiated class $base."));
     return new FlatTypeMask.nonNullExact(base);
   }