Fix V8 isolate setup in embedder tests and roll V8 to 055bfa7.

testing/js_embedder_test.cpp

Index: testing/js_embedder_test.cpp
diff --git a/testing/js_embedder_test.cpp b/testing/js_embedder_test.cpp
index ffa647d0730d6b25cc7b659816d0318d185058d2..4815cd54a3fa2e5eb4e65f839ee35028e560de75 100644
--- a/testing/js_embedder_test.cpp
+++ b/testing/js_embedder_test.cpp
@@ -5,17 +5,16 @@
 #include "testing/js_embedder_test.h"
 
 JSEmbedderTest::JSEmbedderTest()
-    : m_pArrayBufferAllocator(new FXJS_ArrayBufferAllocator) {
+    : m_pArrayBufferAllocator(new FXJS_ArrayBufferAllocator),
+      m_pIsolate(nullptr) {}
+
+JSEmbedderTest::~JSEmbedderTest() {}
+
+void JSEmbedderTest::SetUp() {
   v8::Isolate::CreateParams params;
   params.array_buffer_allocator = m_pArrayBufferAllocator.get();
   m_pIsolate = v8::Isolate::New(params);
-}
 
-JSEmbedderTest::~JSEmbedderTest() {
-  m_pIsolate->Dispose();
-}
-
-void JSEmbedderTest::SetUp() {
   EmbedderTest::SetExternalIsolate(m_pIsolate);
   EmbedderTest::SetUp();
 
@@ -34,6 +33,8 @@ void JSEmbedderTest::TearDown() {
   m_pPersistentContext.Reset();
   FXJS_Release();
   EmbedderTest::TearDown();
+  m_pIsolate->Dispose();
+  m_pIsolate = nullptr;
 }
 
 v8::Isolate* JSEmbedderTest::isolate() {