dart2js cps: Support function types in 'is' and 'as' operators.

sdk/lib/_internal/compiler/js_lib/js_rti.dart

Index: sdk/lib/_internal/compiler/js_lib/js_rti.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_rti.dart b/sdk/lib/_internal/compiler/js_lib/js_rti.dart
index f1531501070267101dc1ecb65b3443f12d4b375a..e5669e2a6babfca6dfcb3b2d8269714294549f74 100644
--- a/sdk/lib/_internal/compiler/js_lib/js_rti.dart
+++ b/sdk/lib/_internal/compiler/js_lib/js_rti.dart
@@ -389,7 +389,8 @@ bool checkSubtypeOfRuntimeType(o, t) {
     rti = JS('JSExtendableArray', '#.slice()', rti);  // Make a copy.
     JS('', '#.splice(0, 0, #)', rti, type);  // Insert type at position 0.
     type = rti;
-  } else if (isDartFunctionType(t)) {
+  }
+  if (isDartFunctionType(t)) {

[asgerf, 2015/06/17 14:01:49]

This matters when 'o' is a generic class with a call method being tested against
a function type.

[karlklose, 2015/06/18 07:45:02]

Is this change not affecting the SSA backend because it builds the function type
test objects instead?

[asgerf, 2015/06/18 09:20:38]

For direct checks against a function type, yes.

However, if testing against a type variable holding a function type at runtime,
SSA calls this method and would previously give the wrong answer, but is now
fixed.

I've added a new test case that fails without the change but passes now.

     // Functions are treated specially and have their type information stored
     // directly in the instance.
     var targetSignatureFunction =