[unittests] Fix build/namespaces style guide violation.

test/unittests/compiler/typer-unittest.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <functional>
 
 #include "src/codegen.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/operator-properties.h"
 #include "test/cctest/types-fuzz.h"
 #include "test/unittests/compiler/graph-unittest.h"
 
-using namespace v8::internal;
-using namespace v8::internal::compiler;
-
+namespace v8 {
+namespace internal {
+namespace compiler {
 
 // TODO(titzer): generate a large set of deterministic inputs for these tests.
 class TyperTest : public TypedGraphTest {
  public:
   TyperTest()
       : TypedGraphTest(3),
         types_(zone(), isolate(), random_number_generator()),
         javascript_(zone()) {
     context_node_ = graph()->NewNode(common()->Parameter(2), graph()->start());
     rng_ = random_number_generator();
@@ skipping 383 matching lines @@
 
 
 TEST_F(TyperTest, TypeRegressInt32Constant) {
   int values[] = {-5, 10};
   for (auto i : values) {
     Node* c = graph()->NewNode(common()->Int32Constant(i));
     Type* type = NodeProperties::GetType(c);
     EXPECT_TRUE(type->Is(NewRange(i, i)));
   }
 }
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8