Check arguments counts.

sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart

Index: sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart b/sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart
index 89c2a58dd8b3170a7d9e31effd00c95624cd5715..2ad4a1e8890ab3358ff344f853f169256dd95784 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/foreign_helper.dart
@@ -87,8 +87,11 @@ library _foreign_helper;
  * optimizations around the code.  This might be an extension of [JS] or a new
  * function similar to [JS] with additional arguments for the new information.
  */
+// Add additional optional arguments if needed. The method is treated internally
+// as a variable argument method.
 dynamic JS(String typeDescription, String codeTemplate,
-    [var arg0, var arg1, var arg2]) {}
+    [var arg0, var arg1, var arg2, var arg3, var arg4, var arg5, var arg6,
+     var arg7, var arg8, var arg9, var arg10, var arg11]) {}
 
 /**
  * Returns the isolate in which this code is running.