Use failedAt in more places

pkg/compiler/lib/src/resolution/registry.dart

Index: pkg/compiler/lib/src/resolution/registry.dart
diff --git a/pkg/compiler/lib/src/resolution/registry.dart b/pkg/compiler/lib/src/resolution/registry.dart
index cc9db2c00894e5e5bd57d51d3fa77e9682bc95e1..26b592c0e9a1b0a9096f48b238469ac85b1d524a 100644
--- a/pkg/compiler/lib/src/resolution/registry.dart
+++ b/pkg/compiler/lib/src/resolution/registry.dart
@@ -279,22 +279,22 @@ class ResolutionRegistry {
 
   /// Register [node] to be the declaration of [target].
   void defineTarget(Node node, JumpTarget target) {
-    assert(invariant(node, node is Statement || node is SwitchCase,
-        message: "Only statements and switch cases can define targets."));
+    assert(node is Statement || node is SwitchCase,
+        failedAt(node, "Only statements and switch cases can define targets."));
     mapping.defineTarget(node, target);
   }
 
   /// Returns the [JumpTarget] defined by [node].
   JumpTarget getTargetDefinition(Node node) {
-    assert(invariant(node, node is Statement || node is SwitchCase,
-        message: "Only statements and switch cases can define targets."));
+    assert(node is Statement || node is SwitchCase,
+        failedAt(node, "Only statements and switch cases can define targets."));
     return mapping.getTargetDefinition(node);
   }
 
   /// Undefine the target of [node]. This is used to cleanup unused targets.
   void undefineTarget(Node node) {
-    assert(invariant(node, node is Statement || node is SwitchCase,
-        message: "Only statements and switch cases can define targets."));
+    assert(node is Statement || node is SwitchCase,
+        failedAt(node, "Only statements and switch cases can define targets."));
     mapping.undefineTarget(node);
   }