Use failedAt in more places

pkg/compiler/lib/src/io/position_information.dart

Index: pkg/compiler/lib/src/io/position_information.dart
diff --git a/pkg/compiler/lib/src/io/position_information.dart b/pkg/compiler/lib/src/io/position_information.dart
index 0c94faa51f68dd0cb6447d8b03a84e63282ed5cb..d9910fbdf0fb327c907c3834897451b0405cb313 100644
--- a/pkg/compiler/lib/src/io/position_information.dart
+++ b/pkg/compiler/lib/src/io/position_information.dart
@@ -653,8 +653,11 @@ class CallPosition {
       return new CallPosition(
           node.target, CodePositionKind.END, SourcePositionKind.INNER);
     } else {
-      assert(invariant(NO_LOCATION_SPANNABLE, false,
-          message: "Unexpected property access ${nodeToString(node)}:\n"
+      assert(

[Johnni Winther, 2017/05/24 08:24:52]

Add a TODO for me to maybe remove this assertion.

[sra1, 2017/05/24 17:38:54]

Done.

+          false,
+          failedAt(
+              NO_LOCATION_SPANNABLE,
+              "Unexpected property access ${nodeToString(node)}:\n"
               "${DebugPrinter.prettyPrint(node)}"));
       // Don't know....
       return new CallPosition(