cctest: put some types into anonymous namespace.

This is to prevent a collision with Expectations class defined in test-field-type-tracking.cc, which happens in Clang under certain conditions (official build + Precise + unknown).

While the original intent was to just workaround the Clang bug, putting types into anonymous namespace seems reasonable anyway (thank you to Benedikt Meurer for the suggestion!)

BUG=630335

Review-Url: https://codereview.chromium.org/2227073002
Cr-Commit-Position: refs/heads/master@{#38552}

test/cctest/test-decls.cc

@@ -34,6 +34,7 @@
 
 using namespace v8;
 
+namespace {
 
 enum Expectations {
   EXPECT_RESULT,
@@ -223,6 +224,7 @@ v8::Local<Integer> DeclarationContext::Query(Local<Name> key) {
   return v8::Local<Integer>();
 }
 
+}  // namespace
 
 // Test global declaration of a property the interceptor doesn't know
 // about and doesn't handle.