When metadata is not requested, elide unneeded signatures

pkg/dev_compiler/test/codegen_expected/destructuring.js

Index: pkg/dev_compiler/test/codegen_expected/destructuring.js
diff --git a/pkg/dev_compiler/test/codegen_expected/destructuring.js b/pkg/dev_compiler/test/codegen_expected/destructuring.js
index e9365d30653d60ef5286624292908d2e9cf50b74..46b4899b71a1c5340f37943721af884a441ea7c8 100644
--- a/pkg/dev_compiler/test/codegen_expected/destructuring.js
+++ b/pkg/dev_compiler/test/codegen_expected/destructuring.js
@@ -75,9 +75,6 @@ define(['dart_sdk'], function(dart_sdk) {
     new() {
     }
   };
-  dart.setSignature(src__varargs._Rest, {
-    constructors: () => ({new: dart.definiteFunctionType(src__varargs._Rest, [])})
-  });
   src__varargs.rest = dart.const(new src__varargs._Rest());
   src__varargs.spread = function(args) {
     dart.throw(new core.StateError('The spread function cannot be called, ' + 'it should be compiled away.'));