Add closure object type to debugger wire protocol

runtime/vm/debugger_api_impl_test.cc

Index: runtime/vm/debugger_api_impl_test.cc
===================================================================
--- runtime/vm/debugger_api_impl_test.cc	(revision 30163)
+++ runtime/vm/debugger_api_impl_test.cc	(working copy)
@@ -1887,17 +1887,19 @@
   Dart_Handle clo = Invoke("main");
   EXPECT_VALID(clo);
   EXPECT(Dart_IsClosure(clo));
-  Dart_Handle name;
+  Dart_Handle name, sig;
   Dart_CodeLocation loc;
   loc.script_url = Dart_Null();
   loc.library_id = -1;
   loc.token_pos = -1;
-  Dart_Handle res = Dart_GetClosureInfo(clo, &name, &loc);
+  Dart_Handle res = Dart_GetClosureInfo(clo, &name, &sig, &loc);
   EXPECT_VALID(res);
   EXPECT_TRUE(res);
   EXPECT_VALID(name);
   EXPECT(Dart_IsString(name));
   EXPECT_STREQ("foo", ToCString(name));
+  EXPECT(Dart_IsString(sig));
+  EXPECT_STREQ("() => void", ToCString(sig));
   EXPECT(Dart_IsString(loc.script_url));
   EXPECT_STREQ("dart:test-lib", ToCString(loc.script_url));
   EXPECT_EQ(0, loc.token_pos);