Move compiler cctests into v8::internal::compiler namespace.

test/cctest/compiler/test-changes-lowering.cc

Index: test/cctest/compiler/test-changes-lowering.cc
diff --git a/test/cctest/compiler/test-changes-lowering.cc b/test/cctest/compiler/test-changes-lowering.cc
index 7ae9e1170bbbb280aaa0f1603d1c46423b8813d3..028ac4b7c868819f0db1569e71255e1ca0c815ab 100644
--- a/test/cctest/compiler/test-changes-lowering.cc
+++ b/test/cctest/compiler/test-changes-lowering.cc
@@ -27,8 +27,9 @@
 #include "test/cctest/compiler/graph-builder-tester.h"
 #include "test/cctest/compiler/value-helper.h"
 
-using namespace v8::internal;
-using namespace v8::internal::compiler;
+namespace v8 {
+namespace internal {
+namespace compiler {
 
 template <typename ReturnType>
 class ChangesLoweringTester : public GraphBuilderTester<ReturnType> {
@@ -286,3 +287,7 @@ TEST(RunChangeBitToBool) {
     CHECK_EQ(false_obj, result);
   }
 }
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8