Unify the way cctest initalizes the VM for each test case.

test/cctest/test-assembler-x64.cc

Index: test/cctest/test-assembler-x64.cc
diff --git a/test/cctest/test-assembler-x64.cc b/test/cctest/test-assembler-x64.cc
index d2ea771588c9ec7313cd41e9b5dba75a49ee44bb..669475ad8aba17dd4b4f4dd1f8ffe2c6bab7f933 100644
--- a/test/cctest/test-assembler-x64.cc
+++ b/test/cctest/test-assembler-x64.cc
@@ -88,16 +88,6 @@ static const v8::internal::Register arg2 = rsi;
 #define __ assm.
 
 
-static v8::Persistent<v8::Context> env;
-
-
-static void InitializeVM() {
-  if (env.IsEmpty()) {
-    env = v8::Context::New();
-  }
-}
-
-
 TEST(AssemblerX64ReturnOperation) {
   OS::SetUp();
   // Allocate an executable page of memory.
@@ -361,8 +351,8 @@ TEST(OperandRegisterDependency) {
 
 TEST(AssemblerX64LabelChaining) {
   // Test chaining of label usages within instructions (issue 1644).
-  InitializeVM();
-  v8::HandleScope scope(env->GetIsolate());
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
   Assembler assm(Isolate::Current(), NULL, 0);
 
   Label target;
@@ -374,8 +364,8 @@ TEST(AssemblerX64LabelChaining) {
 
 
 TEST(AssemblerMultiByteNop) {
-  InitializeVM();
-  v8::HandleScope scope(env->GetIsolate());
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
   v8::internal::byte buffer[1024];
   Isolate* isolate = Isolate::Current();
   Assembler assm(isolate, buffer, sizeof(buffer));