Fix VariableDefinitions.endToken for formal parameters.

sdk/lib/_internal/compiler/implementation/tree/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/tree/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/tree/nodes.dart b/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
index 9de0183165e8acfc46c80a9dc23390a572f940d9..f8bb1aadbd79efd131576aefcf79d039a40d5cb3 100644
--- a/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/tree/nodes.dart
@@ -1092,7 +1092,12 @@ class VariableDefinitions extends Statement {
     return token;
   }
 
-  Token getEndToken() => endToken;
+  Token getEndToken() {
+    if (endToken == null) {
+      return definitions.getEndToken();
+    }
+    return endToken;
+  }
 }
 
 abstract class Loop extends Statement {